Isotope-enriched 3-amino-1-propanesulfonic acid derivatives and uses thereof

ABSTRACT

There are provided isotope-enriched compounds of Formula (I) and pharmaceutically acceptable salts or esters thereof, as well as pharmaceutical compositions thereof and methods of use thereof for prevention and treatment of amyloid-β related diseases, such as Alzheimer&#39;s disease.
 
R 1 R 2 X—CR 2 —CH 2 —CH 2 —SO 3 H   (I)

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority to Chinese applicationno. 201710168819.2 filed Mar. 21, 2017, the entire contents of which arehereby incorporated by reference.

FIELD

The present disclosure relates to isotope-enriched3-amino-1-propanesulfonic acid (3APS) and derivatives, compositionsthereof, and methods of use thereof in therapeutic applications such asthe prevention and treatment of Alzheimer's disease.

BACKGROUND

Alzheimer's disease (AD) is a progressive degenerative disease of thebrain primarily associated with aging. Prevalence of AD in the UnitedStates in 2000 was close to 4.5 Million. It has been estimated thatapproximately one in ten individuals over 65 and nearly half of thoseover 85 are affected by AD. Approximately 360,000 patients will bediagnosed with AD each year in the United States alone.

Clinical presentation of AD is characterized by loss of memory,cognition, reasoning, judgment, and orientation. As the diseaseprogresses, motor, sensory, and linguistic abilities are also affecteduntil there is global impairment of multiple cognitive functions. Thesecognitive losses occur gradually, but typically lead to severeimpairment and eventual death in the range of four to twelve years.

Alzheimer's disease (AD) is characterized by two major pathologicobservations in the brain: neurofibrillary tangles and beta amyloid (orneuritic) plaques, comprised predominantly of an aggregate of a peptidefragment known as Aβ. Individuals with AD exhibit characteristicbeta-amyloid deposits in the brain (beta amyloid plaques) and incerebral blood vessels (beta amyloid angiopathy) as well asneurofibrillary tangles. Neurofibrillary tangles occur not only inAlzheimer's disease but also in other dementia-inducing disorders.

3-amino-1-propanesulfonic acid (also known as 3APS, Tramiprosate, andAlzhemed™) is a promising investigational product candidate for thetreatment of Alzheimer's disease. 3APS was the subject of Phase IIIclinical trials in North America and Europe (Wright, T. M., Drugs ofToday (2006), 42(5): 291-298). Results from these clinical studies havebeen published (Journal of Nutrition, Health & Aging (2009), 13(6),550-557; Journal of Nutrition, Health & Aging (2009), 13(9), 808-812;Archives of Medical Science (2011), 7(1), 102-111; Journal ofAlzheimer's Disease (2016), 50(3), 807-816; Aging: Clinical andExperimental Research (2012), 24(6), 580-587).

3APS is believed to act by reducing amyloid aggregation, depositionand/or load of amyloid in the brain through its binding to soluble Aβpeptide. It is known that 3APS is metabolized both in vitro and in vivo(U.S. Pat. No. 8,748,656). 3APS is extensively metabolized in vivo toproduce three potential metabolites: 2-carboxyethanesulfonic acid,3-hydroxy-1-propanesulfonic acid, and 3-acetylamino-1-propansulfonicacid. The only major metabolite of 3APS produced in mice, rats, dogs,and humans is 2-carboxyethanesulfonic acid. This metabolism of 3APS hassignificant effect on its pharmacokinetic profile and accordingly itspharmaceutical efficacy. In order to increase therapeutic effectivenessof 3APS, attempts have been made to increase overall bioavailability,for example by increasing stability or reducing metabolism. One suchapproach is the use of prodrugs and derivatives of 3APS that willgenerate 3APS in vivo after administration to a subject (see, forexample, U.S. Pat. No. 8,748,656 and PCT International ApplicationPublication No. WO 2015/143447, the contents of which are herebyincorporated by reference in their entirety).

Foreign substances including compounds and other therapeutic agents areoften metabolized to facilitate their elimination from the body. Forexample, various enzymes such as cytochrome P₄₅₀ enzymes, esterases,proteases, reductases, dehydrogenases, transaminases, and monoamineoxidases, can react with foreign substances and catalyze theirconversion to more polar metabolites for renal excretion. The resultantmetabolites can have substantially different pharmacokinetic,pharmacodynamic, and acute and long-term toxicity profiles relative tothe parent compounds.

Such metabolic reactions frequently involve the oxidation of acarbon-hydrogen bond to a carbon-oxygen or a carbon-carbon n-bond.Carbon-hydrogen bond strength is directly proportional to the absolutevalue of the ground-state vibrational energy of the bond. Thisvibrational energy depends on the mass of the atoms that form the bondand increases as the mass of one or both of the atoms making the bondincreases. Since deuterium (D) has twice the mass of protium (¹H), acarbon-deuterium (C-D) bond is stronger than the correspondingcarbon-protium (C-¹H) bond. If a C-¹H bond is broken during arate-determining step of a metabolic reaction, then substituting adeuterium for that protium will cause a decrease in the reaction rate.

Deuterium is a stable and non-radioactive isotope of hydrogen which hasapproximately twice the mass of protium, which is the most commonisotope of hydrogen. Deuteration of pharmaceuticals to improvepharmacokinetics and pharmacodynamics has been demonstrated previously.For example, SD-809, a deuterated drug (deutetrabenazine), has been usedfor the treatment of Huntington's disease. Such isotope-enrichment canpotentially affect a therapeutic agent's metabolism, release fromprodrugs and derivatives, absorption, and/or clearance, significantlyaltering the agent's pharmacokinetic profile.

SUMMARY

It is an object of the present invention to ameliorate at least some ofthe deficiencies present in the prior art. Embodiments of the presenttechnology have been developed based on the inventors' appreciation thatthere is a need for increasing the therapeutic efficacy of 3APS, forexample by increasing bioavailability, stability, and/or reducingmetabolism of the compound. These and other needs can be satisfied bythe disclosure herein of isotope-enriched 3-amino-1-propanesulfonic acid(3APS) derivatives and/or prodrugs, pharmaceutical compositions and usesthereof to treat various Aβ-related disorders.

In a first broad aspect, there are provided compounds of Formula I, orpharmaceutically acceptable salts or esters thereof:R¹R²X—CR₂—CH₂—CH₂—SO₃H   (I)

where: R¹ and R² are independently a hydrogen of natural abundance or aprotecting group that is of natural abundance or isotope-enriched, theprotecting group being selected from acyl, carbonyl, thiocarbonyl, andcarbamoyl groups; X is a nitrogen of natural abundance, an ¹⁵N-enrichednitrogen (¹⁵N) or a combination thereof; and R is a hydrogen of naturalabundance, a deuterium (D) or a combination thereof; provided that R¹,R², X and R are not all atoms of natural abundance (in other words, whenR¹ and R² are atoms of natural abundance, X and R are not both atoms ofnatural abundance, i.e., R is not a hydrogen of natural abundance when Xis a nitrogen of natural abundance. In other words, when R¹ and R² areboth atoms of natural abundance or both comprise at least one atom ofnatural abundance, only one of X and R is an atom of natural abundance:if X is a nitrogen of natural abundance, then R is D; if R is H, then Xis ¹⁵N). In some embodiments, R is a hydrogen of natural abundance and Xis ¹⁵N. In some embodiments, R is D and X is a nitrogen of naturalabundance. In some embodiments, R is D and X is ¹⁵N. In someembodiments, when X and R are atoms of natural abundance, R¹ and R² arenot atoms of natural abundance or do not comprise only atoms orprotecting groups of natural abundance (i.e., at least one of R¹ and R²is isotope-enriched). In one embodiment of Formula (I), R¹ is an aminoacid residue with or without isotope-enrichment and R² is a hydrogen ofnatural abundance.

In one embodiment of Formula (I), R is a hydrogen of natural abundance;X is a nitrogen of natural abundance; and at least one atom in R¹ and/orR² is not of natural abundance.

In a second broad aspect, there are provided compounds of Formula II, orpharmaceutically acceptable salts or esters thereof:H₂X—CR₂—CH₂—CH₂—SO₃H   (II)where X is a nitrogen of natural abundance, an N-15 isotope-enrichednitrogen (also referred to herein as “¹⁵N-enriched nitrogen” or “¹⁵N”)or a combination thereof, and R is a hydrogen of natural abundance, adeuterium (D) or a combination thereof, provided that X and R are notboth atoms of natural abundance at the same time (in other words, R isnot a hydrogen of natural abundance when X is a nitrogen of naturalabundance, e.g., when X is a nitrogen of natural abundance, R is D). Insome embodiments, R is a hydrogen of natural abundance and X is ¹⁵N. Insome embodiments, R is D and X is a nitrogen of natural abundance. Insome embodiments, R is D and X is ¹⁵N.

In a third broad aspect, there are provided compounds of Formula III, orpharmaceutically acceptable salts or esters thereof:

where X and R are as defined above; Y is a carbon of natural abundance,a ¹³C-enriched carbon (¹³C) or a combination thereof; Z is a sulfur, anoxygen of natural abundance, an ¹⁸O-enriched oxygen (¹⁸O), an¹⁷O-enriched oxygen (¹⁷O) or a combination thereof; and R³ is asubstituting group selected from substituted or unsubstituted alkyl,aryl, amino alkyl, amino arylalkyl, heterocyclyl, alkoxyl, alkylthio,alkylamino, acyloxyl, and thioacyloxyl; provided that at least one of X,R, Y and Z is not an atom of natural abundance. In some embodiments, Ris not a hydrogen of natural abundance when X is a nitrogen of naturalabundance.

In one embodiment of Formula (III), R³, Y, and Z taken together form anacyl group connected to X, forming an amide bond linkage. In anotherembodiment, R³ is an amino acid residue and R³, Y, and Z taken togetherform an acyl group connected to X, the acyl group being derived from anamino acid. The amino acid may be an L-amino acid, a D-amino acid, or amixture of L and D forms. The amino acid may be a natural or anunnatural amino acid. In a particular embodiment, the amino acid is anL-amino acid. In an embodiment, the amino acid is a naturally-occurringL-amino acid.

In some embodiments, there are provided compounds of Formulae IV and V,or pharmaceutically acceptable salts or esters thereof:

where R⁴ is a side chain of a natural or unnatural amino acid; O* is anoxygen atom of natural abundance, an ¹⁸O-enriched oxygen (¹⁸O), an¹⁷O-enriched oxygen (¹⁷O) or a combination thereof; and C* is a carbonatom of natural abundance, a ¹³C-enriched carbon (¹³C) or a combinationthereof. The corresponding amino acid may be an L-amino acid, a D-aminoacid, or a mixture of L and D forms. The corresponding amino acid may bea natural or an unnatural amino acid.

In another embodiment, there are provided compounds of Formula VI, orpharmaceutically acceptable salts or esters thereof:

where R⁴ is a side chain of a natural or unnatural amino acid; O^(#) isan oxygen atom of natural abundance, an ¹⁸O-enriched oxygen (¹⁸O), an¹⁷O-enriched oxygen (¹⁷O) or a combination thereof; and C^(#) is acarbon atom of natural abundance, a ¹³C-enriched carbon or a combinationthereof; provided that O^(#) and C^(#) are not both atoms of naturalabundance (in other words, at least one of O^(#) and C^(#) is anisotope-enriched atom, or at least one of O^(#) and C^(#) is not an atomof natural abundance). The corresponding amino acid may be an L-aminoacid, a D-amino acid, or a mixture of L and D forms. The correspondingamino acid may be a natural or unnatural amino acid.

Compounds in which all the atoms or elements in the structure are intheir natural abundance (non-isotope enriched compounds) are notencompassed by the present invention.

In some embodiments, the compound of Formula (I), (III), (IV), (V), or(VI) is not N-acetyl-3-amino-1-propanesulfonic acid.

Compounds provided herein, e.g., compounds of Formula (I), (II), (III),(IV), (V), or (VI), may be enriched for one or more isotope. Any stableor pharmaceutically acceptable isotope may be used to enrich a compoundof the invention. For example, an isotope-enriched compound may compriseD (²H), ¹³C, ¹⁵N, ¹⁷O, and/or ¹⁸O.

In some embodiments, the isotope-enriched compound of Formula (I), (II),(III), (IV), (V), or (VI) is a compound shown in Table 1, Table 2, Table3, or Table 4, or a pharmaceutically-acceptable salt, ester, chelator,hydrate, solvate, stereoisomer, or polymorphic form thereof.

TABLE 1 3,3-Dideuterium-3-amino-1-propanesulfonic acid, ¹⁵N-3-amino-1-propanesulfonic acid and selected derivatives. No. Structure 1

2

3

4

5

6

7

8

9

10

11

12

TABLE 2 Examples of N-(¹⁸O- and ¹⁷O-aminoacylated)3-amino-1-propanesulfonic acid prodrugs. No. Structure 13

14

15

16

17

18

19

20

21

22

TABLE 3 Examples of N-(1-¹³C-aminoacyl)-3-amino-1-propanesulfonic acidprodrugs and selected isotope-enriched prodrugs. No. Structure 23

24

25

26

27

28

29

30

31

32

TABLE 4 Examples of isotope-enriched 3-(histidylamino)-1-propanesulfonicacid. No. Structure 33

34

35

36

37

38

39

40

41

42

In an embodiment, the isotope-enriched compound is3-(acylamino)-3,3-dideuterium-1-propanesulfonic acid or3-(acyl(¹⁵N-amino))-1-propanesulfonic acid, where the acyl group isselected from arginyl, aspartyl, asparigyl, cystyl, glutamyl,glutaminyl, glycyl, isoleucyl, leucyl, lysyl, methionyl, prolyl,selenocystyl, threonyl, tryptophanyl, tyrosyl, and 4-hydroxyisoleucyl;or a pharmaceutically-acceptable salt, ester, chelator, hydrate,solvate, stereoisomer, or polymorphic form thereof.

In another embodiment, the isotope-enriched compound is3-((1-1¹³C-acyl)amino)-1-propanesulfonic acid,3-((1-¹⁸O-acyl)amino)-1-propanesulfonic acid, or3-((1-¹⁷O-acyl)amino)-1-propanesulfonic acid, where the acyl group isselected from arginyl, aspartyl, asparigyl, cystyl, glutamyl,glutaminyl, glycyl, isoleucyl, leucyl, lysyl, methionyl, prolyl,selenocystyl, threonyl, tryptophanyl, tyrosyl, and 4-hydroxyisoleucyl;or a pharmaceutically-acceptable salt, ester, chelator, hydrate,solvate, stereoisomer, or polymorphic form thereof.

In some embodiments, the compounds of the present invention are in theiroriginal acid or base forms, such as amino sulfonic acid. In otherembodiments, the compounds of the present invention encompass otherpharmaceutically accepted forms or the original form, such as inorganicsalt, organic salt, ester, chelator, hydrate, or solvate. The inventionalso encompasses different polymorphic forms of compounds according toFormulae I to VI and Tables 1-4.

Without wishing to be limited by theory, it is believed thatisotope-enriched derivatives and/or prodrugs of 3APS provided herein canimprove therapeutic efficacy of 3APS by improving its therapeuticbio-distribution and/or pharmacokinetic profiles, for example byincreasing bioavailability of the compound, reducing metabolism of thecompound, increasing compound stability, and/or changing the releaserate of 3APS from a prodrug.

According to another broad aspect, there are provided methods forincreasing the therapeutic effectiveness of 3APS comprisingadministering to a subject, preferably a human subject, an effectiveamount of an isotope-enriched 3APS derivative as described herein, or aprodrug that releases an isotope-enriched 3APS derivative in thesubject.

In some embodiments of methods provided herein, the compound is acompound of any one of Formulae (I)-(VI) as described herein, or apharmaceutically acceptable salt thereof. In some embodiments of methodsprovided herein, the compound is a compound of any one of Formulae(I)-(VI) as described herein, or a pharmaceutically acceptable saltthereof, wherein the compound is not N-acetyl-3-amino-1-propanesulfonicacid.

According to an aspect, there are provided compounds and compositionsthat will yield or generate 3APS or isotope-enriched 3APS afteradministration to a subject. Such compounds, pharmaceutical compositionscontaining such compounds, and methods employing such compounds andcompositions in the treatment of various amyloid-β related diseases andconditions such as Alzheimer's disease are provided herein.

In another broad aspect, there are provided pharmaceutical compositionscomprising a compound described herein, or a pharmaceutically acceptablesalt thereof, and a pharmaceutically acceptable carrier. In someembodiments, there are provided pharmaceutical compositions comprising acompound of any one of Formulae I-VI, or a pharmaceutically acceptablesalt thereof, and a pharmaceutically acceptable carrier. In someembodiments, there are provided pharmaceutical compositions comprising acompound of any one of Formulae I-VI, or a pharmaceutically acceptablesalt thereof, and a pharmaceutically acceptable carrier, wherein thecompound is not N-acetyl-3-amino-1-propanesulfonic acid.

In some embodiments, compounds of Formulae (I)-(VI) can act to increasethe therapeutic effectiveness of 3APS in a subject, as compared toadministration of 3APS that is not isotope-enriched (i.e., in which allthe atoms in the 3APS compound are in their natural abundance). In someembodiments, compounds of Formulae (I)-(VI) can act to increase thebioavailability of 3APS, the AUC of 3APS, the brain levels of 3APS, theCSF levels of 3APS, the C_(max) of 3APS, the T_(max) of 3APS, thestability of 3APS, the therapeutic bio-distribution of 3APS, and/or thebioabsorption of 3APS in a subject, as compared to administration of3APS that is not isotope-enriched. In some embodiments, the effectivetherapeutic level of 3APS in a selected human tissue such as brain orCSF is increased after administration of a compound of any of Formulae(I)-(VI), as compared to administration of 3APS that is notisotope-enriched. In some embodiments, compounds of Formulae (I)-(VI)can act to reduce the metabolism of 3APS in a subject, as compared toadministration of 3APS that is not isotope-enriched. In someembodiments, compounds of Formulae (I)-(VI) can act to reduce the sideeffects of 3APS in a subject, as compared to administration of 3APS thatis not isotope-enriched.

In some embodiments, compounds of Formulae (I)-(VI) and compositionsthereof are used to prevent or treat an amyloid-β related disease orcondition such as Alzheimer's disease in a subject. In some embodiments,compounds of Formulae (I)-(VI) inhibit amyloid-β deposition,oligomerization, and/or toxicity, and/or improve clinical parametersassociated with an amlyoid-β related disease or condition (such asperformance on cognitive tests).

In some embodiments, administration of compounds and compositions of theinvention may improve the therapeutic bio-distribution of 3APS in thesubject as compared to administration of the same equivalent molar doseof non-isotope enriched 3APS or a non-isotope enriched prodrug of 3APS.For example, the bioavailability of 3APS may be improved, the stabilityof 3APS may be improved, the metabolism of 3APS may be reduced, or therelease rate of 3APS from a prodrug may be improved, as compared toadministration of the same equivalent molar dose of non-isotope enriched3APS or a non-isotope enriched prodrug of 3APS. In an embodiment, theoral AUC of 3APS in the subject is improved (e.g., increased by at leastabout 2%, about 5%, about 10%, or about 20%), as compared to the oralAUC after administration of the same equivalent molar dose ofnon-isotope enriched 3APS or a non-isotope enriched prodrug of 3APS.

In a further aspect, there are provided kits for treating an amyloid-βrelated disease in a subject in need thereof, comprising a compound (ora pharmaceutically acceptable salt thereof) or a pharmaceuticalcomposition, as described herein; optionally one or more additionalcomponent such as acids, bases, buffering agents, inorganic salts,solvents, antioxidants, preservatives, or metal chelators; andinstructions for use thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show more clearly howit may be carried into effect, reference will now be made by way ofexample to the accompanying drawings, which illustrate aspects andfeatures according to embodiments of the present invention, and inwhich:

FIG. 1 shows plasma concentration-time curves of the compound followingan oral administration of 3APS (non-isotope enriched), compound 1, andcompound 4, including the concentration-time curve of compound 4 in thesame experiment. Curves labeled with -♦-, -▪-, and -▴- represent plasmadrug concentration following administration of 3APS (of naturalabundance), compound 1 and compound 4, respectively; and the curvelabeled with -x- represents plasma prodrug concentration followingadministration of compound 4. The figure shows that at themole-equivalent oral dose, the isotope-enriched compound 1 had a delayedmetabolic profile and an improved exposure compared to 3APS, whilecompound 4 demonstrated even greater improvement of drug exposure.

FIG. 2 shows the plasma concentration of the metabolite (M,2-carboxy-1-ethanesulfonic acid) following an oral administration ofnon-isotope enriched 3APS (3APS of natural abundance), compound 1, andcompound 4, respectively. Curves labeled with -♦-, -▪-, and -▴-represent 3APS (of natural abundance), compound 1, and compound 4,respectively. All compounds were administered at a molar-equivalent dose(0.72 mmol/kg).

DETAILED DESCRIPTION

In order to provide a clear and consistent understanding of the termsused in the present specification, a number of definitions are providedbelow. Moreover, unless defined otherwise, all technical and scientificterms as used herein have the same meaning as commonly understood to oneof ordinary skill in the art to which this invention pertains.

The use of the word “a” or “an” when used in conjunction with the term“comprising” in the claims and/or the specification may mean “one”, butit is also consistent with the meaning of “one or more”, “at least one”,and “one or more than one”. Similarly, the word “another” may mean atleast a second or more.

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “include” and “includes”) or “containing”(and any form of containing, such as “contain” and “contains”), areinclusive or open-ended and do not exclude additional, unrecitedelements or process steps.

The term “about” is used to indicate that a value includes an inherentvariation of error for the device or the method being employed todetermine the value.

The term “derivative” as used herein, is understood as being a substancesimilar in structure to another compound but differing in some slightstructural detail.

The present description refers to a number of chemical terms andabbreviations used by those skilled in the art. Nevertheless,definitions of selected terms are provided for clarity and consistency.

As used herein, the term “alkyl” refers to saturated hydrocarbons havingfrom one to twelve carbon atoms, including linear, branched, and cyclicalkyl groups. Examples of alkyl groups include, without limitation,methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl,decyl, isopropyl, tert-butyl, sec-butyl, isobutyl, cyclopropyl,cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and the like. The termalkyl includes both unsubstituted alkyl groups and substituted alkylgroups. The term “C₁-C_(n)alkyl”, wherein n is an integer from 2 to 12,refers to an alkyl group having from 1 to the indicated “n” number ofcarbon atoms. Alkyl residues may be substituted or unsubstituted. Insome embodiments, for example, alkyl may be substituted by hydroxyl,amino, carboxyl, carboxylic ester, amide, carbamate, or aminoalkyl.

As used herein, the term “acyclic” refers to an organic moiety without aring system. The term “aliphatic group” includes organic moietiescharacterized by straight or branched-chains, typically having between 1and 15 carbon atoms. Aliphatic groups include non-cyclic alkyl groups,alkenyl groups, and alkynyl groups.

As used herein, the term “alkenyl” refers to unsaturated hydrocarbonshaving from two to twelve carbon atoms, including linear, branched, andcyclic non aromatic alkenyl groups, and comprising between one to sixcarbon-carbon double bonds. Examples of alkenyl groups include, withoutlimitation, vinyl, allyl, 1-propen-2-yl, 1-buten-3-yl, 1-buten-4-yl,2-buten-4-yl, 1-penten-5-yl, 1,3-pentadien-5-yl, cyclopentenyl,cyclohexenyl, ethylcyclopentenyl, ethylcylohexenyl, and the like. Theterm alkenyl includes both unsubstituted alkenyl groups and substitutedalkenyl groups. The term “C₂-C_(n)alkenyl”, wherein n is an integer from3 to 12, refers to an alkenyl group having from 2 to the indicated “n”number of carbon atoms.

As used herein, the term “alkynyl” refers to unsaturated hydrocarbonshaving from two to twelve carbon atoms, including linear, branched, andcyclic non aromatic alkynyl groups, and comprising between one to sixcarbon-carbon triple bonds. Examples of alkynyl groups include, withoutlimitation, ethynyl, 1-propyn-3-yl, 1-butyn-4-yl, 2-butyn-4-yl,1-pentyn-5-yl, 1,3-pentadiyn-5-yl, and the like. The term alkynylincludes both unsubstituted alkynyl groups and substituted alkynylgroups. The term “C₂-C_(n)alkynyl”, wherein n is an integer from 3 to12, refers to an alkynyl group having from 2 to the indicated “n” numberof carbon atoms.

Unless the number of carbons is otherwise specified, “lower” as in“lower aliphatic,” “lower alkyl,” “lower alkenyl,” and “lower alkylnyl”,as used herein means that the moiety has at least one (two for alkenyland alkynyl) and equal or less than 6 carbon atoms.

The terms “cycloalkyl”, “alicyclic”, “carbocyclic” and equivalentexpressions refer to a group comprising a saturated or partiallyunsaturated carbocyclic ring in a single, spiro (sharing one atom), orfused (sharing at least one bond) carbocyclic ring system having fromthree to fifteen ring members. Examples of cycloalkyl groups include,without limitation, cyclopropyl, cyclobutyl, cyclopentyl,cyclopenten-1-yl, cyclopenten-2-yl, cyclopenten-3-yl, cyclohexyl,cyclohexen-1-yl, cyclohexen-2-yl, cyclohexen-3-yl, cycloheptyl,bicyclo[4,3,0]nonanyl, norbornyl, and the like. The term cycloalkylincludes both unsubstituted cycloalkyl groups and substituted cycloalkylgroups. The term “C₃-C_(n)cycloalkyl”, wherein n is an integer from 4 to15, refers to a cycloalkyl group having from 3 to the indicated “n”number of carbon atoms in the ring structure. Unless the number ofcarbons is otherwise specified, “lower cycloalkyl” groups as hereinused, have at least 3 and equal or less than 8 carbon atoms in theirring structure.

Cycloalkyl residues can be saturated or contain one or more double bondswithin the ring system. In particular they can be saturated or containone double bond within the ring system. In unsaturated cycloalkylresidues the double bonds can be present in any suitable positions.Monocycloalkyl residues are, for example, cyclopropyl, cyclobutyl,cyclopentyl, cyclopentenyl, cyclohexyl, cyclohexenyl, cycloheptyl,cycloheptenyl, cyclooctyl, cyclononyl, cyclodecyl, cycloundecyl,cyclododecyl or cyclotetradecyl, which can also be substituted, forexample by C₁₋₄ alkyl. Examples of substituted cycloalkyl residues are4-methylcyclohexyl and 2,3-dimethylcyclopentyl. Examples of parentstructures of bicyclic ring systems are norbornane,bicyclo[2.2.1]heptane, bicyclo[2.2.2]octane and bicyclo[3.2.1]octane.

The term “heterocycloalkyl” and equivalent expressions refer to a groupcomprising a saturated or partially unsaturated carbocyclic ring in asingle, spiro (sharing one atom), or fused (sharing at least one bond)carbocyclic ring system having from three to fifteen ring members,including one to six heteroatoms (e.g., N, O, S, P) or groups containingsuch heteroatoms (e.g., NH, NR_(x) (R_(x) is alkyl, acyl, aryl,heteroaryl or cycloalkyl), PO₂, SO, SO₂, and the like). Heterocycloalkylgroups may be C-attached or heteroatom-attached (e.g., via a nitrogenatom) where such is possible. Examples of heterocycloalkyl groupsinclude, without limitation, pyrrolidino, tetrahydrofuranyl,tetrahydrodithienyl, tetrahydropyranyl, tetrahydrothiopyranyl,piperidino, morpholino, thiomorpholino, thioxanyl, piperazinyl,azetidinyl, oxetanyl, thietanyl, homopiperidinyl, oxepanyl, thiepanyl,oxazepinyl, diazepinyl, thiazepinyl, 1,2,3,6-tetrahydropyridinyl,2-pyrrolinyl, 3-pyrrolinyl, indolinyl, 2H-pyranyl, 4H-pyranyl, dioxanyl,1,3-dioxolanyl, pyrazolinyl, dithianyl, dithiolanyl, dihydropyranyl,dihydrothienyl, dihydrofuranyl, pyrazolidinyl, imidazolinyl,imidazolidinyl, 3-azabicyclo[3,1,0]hexanyl, 3-azabicyclo[4,1,0]heptanyl,3H-indolyl, quinolizinyl, and sugars, and the like. The termheterocycloalkyl includes both unsubstituted heterocycloalkyl groups andsubstituted heterocycloalkyl groups. The term“C₃-C_(n)heterocycloalkyl”, wherein n is an integer from 4 to 15, refersto a heterocycloalkyl group having from 3 to the indicated “n” number ofatoms in the ring structure, including at least one hetero group or atomas defined above. Unless the number of carbons is otherwise specified,“lower heterocycloalkyl” groups as herein used, have at least 3 andequal or less than 8 carbon atoms in their ring structure.

The terms “aryl” and “aryl ring” refer to aromatic groups having“4n+2”.pi.(pi) electrons, wherein n is an integer from 1 to 3, in aconjugated monocyclic or polycyclic system (fused or not) and having sixto fourteen ring atoms. A polycyclic ring system includes at least onearomatic ring. Aryl may be directly attached, or connected via aC₁-C₃alkyl group (also referred to as arylalkyl or aralkyl). Examples ofaryl groups include, without limitation, phenyl, benzyl, phenetyl,1-phenylethyl, tolyl, naphthyl, biphenyl, terphenyl, indenyl,benzocyclooctenyl, benzocycloheptenyl, azulenyl, acenaphthylenyl,fluorenyl, phenanthernyl, anthracenyl, and the like. The term arylincludes both unsubstituted aryl groups and substituted aryl groups. Theterm “C₆-C_(n)aryl”, wherein n is an integer from 6 to 15, refers to anaryl group having from 6 to the indicated “n” number of atoms in thering structure, including at least one hetero group or atom as definedabove.

The terms “heteroaryl” and “heteroaryl ring” refer to an aromatic groupshaving “4n+2”.pi.(pi) electrons, wherein n is an integer from 1 to 3, ina conjugated monocyclic or polycyclic system (fused or not) and havingfive to fourteen ring members, including one to six heteroatoms (e.g. N,O, S) or groups containing such heteroatoms (e.g. NH, NR_(x) (R_(x) isalkyl, acyl, aryl, heteroaryl or cycloalkyl), SO, and the like). Apolycyclic ring system includes at least one heteroaromatic ring.Heteroaryls may be directly attached, or connected via a C₁-C₃alkylgroup (also referred to as heteroarylalkyl or heteroaralkyl). Heteroarylgroups may be C-attached or heteroatom-attached (e.g., via a nitrogenatom), where such is possible. Examples of heteroaryl groups include,without limitation, pyridyl, imidazolyl, pyrimidinyl, pyrazolyl,triazolyl, tetrazolyl, furyl, thienyl; isooxazolyl, thiazolyl, oxazolyl,isothiazolyl, pyrrolyl, quinolinyl, isoquinolinyl, indolyl, isoindolyl,chromenyl, isochromenyl, benzimidazolyl, benzofuranyl, cinnolinyl,indazolyl, indolizinyl, phthalazinyl, pyridazinyl, pyrazinyl, triazinyl,isoindolyl, pteridinyl, purinyl, oxadiazolyl, thiadiazolyl, furazanyl,benzofurazanyl, benzothiophenyl, benzothienyl, benzothiazolyl,benzoxazolyl, quinazolinyl, quinolizinyl, quinolonyl, isoquinolonyl,quinoxalinyl, naphthyridinyl, furopyridinyl, carbazolyl,phenanthridinyl, acridinyl, perimidinyl, phenanthrolinyl, phenazinyl,phenothiazinyl, phenoxazinyl, dibenzofuranyl, and the like. The termheteroaryl includes both unsubstituted heteroaryl groups and substitutedheteroaryl groups. The term “C₅-C_(n)heteroaryl”, wherein n is aninteger from 6 to 15, refers to an heteroaryl group having from 5 to theindicated “n” number of atoms in the ring structure, including at leastone hetero group or atom as defined above.

The terms “heterocycle” or “heterocyclic” include heterocycloalkyl andheteroaryl groups. Examples of heterocycles include, without limitation,acridinyl, azocinyl, benzimidazolyl, benzofuranyl, benzothiofuranyl,benzothiophenyl, benzoxazolyl, benzthiazolyl, benztriazolyl,benztetrazolyl, benzisoxazolyl, benzisothiazolyl, benzimidazolinyl,carbazolyl, 4αH-carbazolyl, carbolinyl, chromanyl, chromenyl,cinnolinyl, decahydroquinolinyl, 2H,6H-1,5,2-dithiazinyl,dihydrofuro[2,3-b]tetrahydrofuran, furanyl, furazanyl, imidazolidinyl,imidazolinyl, imidazolyl, 1H-indazolyl, indolenyl, indolinyl,indolizinyl, indolyl, 3H-indolyl, isobenzofuranyl, isochromanyl,isoindazolyl, isoindolinyl, isoindolyl, isoquinolinyl, isothiazolyl,isoxazolyl, methylenedioxyphenyl, morpholinyl, naphthyridinyl,octahydroisoquinolinyl, oxadiazolyl, 1,2,3-oxadiazolyl,1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, 1,3,4-oxadiazolyl, oxazolidinyl,oxazolyl, oxazolidinyl, pyrimidinyl, phenanthridinyl, phenanthrolinyl,phenazinyl, phenothiazinyl, phenoxathiinyl, phenoxazinyl, phthalazinyl,piperazinyl, piperidinyl, piperidonyl, 4-piperidonyl, piperonyl,pteridinyl, purinyl, pyranyl, pyrazinyl, pyrazolidinyl, pyrazolinyl,pyrazolyl, pyridazinyl, pyridooxazole, pyridoimidazole, pyridothiazole,pyridinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolinyl, 2H-pyrrolyl,pyrrolyl, quinazolinyl, quinolinyl, 4H-quinolizinyl, quinoxalinyl,quinuclidinyl, tetrahydrofuranyl, tetrahydroisoquinolinyl,tetrahydroquinolinyl, tetrazolyl, 6H-1,2,5-thiadiazinyl,1,2,3-thiadiazolyl, 1,2,4-thiadiazolyl, 1,2,5-thiadiazolyl,1,3,4-thiadiazolyl, thianthrenyl, thiazolyl, thienyl, thienothiazolyl,thienooxazolyl, thienoimidazolyl, thiophenyl, triazinyl,1,2,3-triazolyl, 1,2,4-triazolyl, 1,2,5-triazolyl, 1,3,4-triazolyl,xanthenyl, and the like. The term heterocycle includes bothunsubstituted heterocyclic groups and substituted heterocyclic groups.

The term “amine” or “amino,” as used herein, refers to an unsubstitutedor substituted moiety of the formula —NR^(a)R^(b), in which R^(a) andR^(b) are each independently hydrogen, alkyl, aryl, or heterocyclyl, orR^(a) and R^(b), taken together with the nitrogen atom to which they areattached, form a heterocyclic ring. The term amino includes compounds ormoieties in which a nitrogen atom is covalently bonded to at least onecarbon or heteroatom. Thus, the terms “alkylamino” and “dialkylamino” asused herein means an amine group having respectively one and at leasttwo C₁-C₆alkyl groups attached thereto. The term “arylamino” and“diarylamino” include groups wherein the nitrogen is bound to at leastone or two aryl groups, respectively. The term “amide” or“aminocarbonyl” includes compounds or moieties which contain a nitrogenatom which is bound to the carbon of a carbonyl or a thiocarbonyl group.The term acylamino refers to an amino group directly attached to an acylgroup as defined herein.

The term “nitro” means —NO₂; the terms “halo” and “halogen” refer tobromine, chlorine, fluorine or iodine substituents; the term “thiol”,“thio”, or “mercapto” means SH; and the term “hydroxyl” or “hydroxy”means —OH. The term “alkylthio” refers to an alkyl group, having asulfhydryl group attached thereto. Suitable alkylthio groups includegroups having 1 to about 12 carbon atoms, preferably from 1 to about 6carbon atoms. The term “alkylcarboxyl” as used herein means an alkylgroup having a carboxyl group attached thereto.

The term “alkoxy” or “lower alkoxy” as used herein means an alkyl grouphaving an oxygen atom attached thereto. Representative alkoxy groupsinclude groups having 1 to about 6 carbon atoms, e.g., methoxy, ethoxy,propoxy, tert-butoxy and the like. Examples of alkoxy groups includemethoxy, ethoxy, isopropyloxy, propoxy, butoxy, pentoxy, fluoromethoxy,difluoromethoxy, trifluoromethoxy, chloromethoxy, dichloromethoxy,trichloromethoxy groups and the like. The term alkoxy includes bothunsubstituted or substituted alkoxy groups, etc., as well asperhalogenated alkyloxy groups.

The term “carbonyl” or “carboxy” includes compounds and moieties whichcontain a carbon connected with a double bond to an oxygen atom.Examples of moieties which contain a carbonyl include aldehydes,ketones, carboxylic acids, amides, esters, anhydrides, etc.

The term “acyl” refers to a carbonyl group that is attached through itscarbon atom to a hydrogen (i.e., formyl), an aliphatic group(C₁-C₆alkyl, C₁-C₆alkenyl, C₁-C₆alkynyl, e.g., acetyl), a cycloalkylgroup (C₃-C₈cycloalkyl), a heterocyclic group (C₃-C₈heterocycloalkyl andC₅-C₆heteroaryl), an aromatic group (C₆aryl, e.g., benzoyl), and thelike. Acyl groups may be unsubstituted or substituted acyl groups (e.g.salicyloyl).

It should be understood that “substitution” or “substituted with”includes the implicit proviso that such substitution is in accordancewith the permitted valence of the substituted atom and the substituent,and that the substitution results in a stable compound, i.e., a compoundwhich does not spontaneously undergo transformation such as byrearrangement, cyclization, elimination, etc. As used herein, the term“substituted” is meant to include all permissible substituents oforganic compounds. In a broad aspect, the permissible substituentsinclude acyclic and cyclic, branched and unbranched, carbocyclic andheterocyclic, aromatic and nonaromatic substituents of organiccompounds. The permissible substituents can be one or more. The term“substituted”, when in association with any of the foregoing groupsrefers to a group substituted at one or more position with substituentssuch as acyl, amino (including simple amino, mono and dialkylamino, monoand diarylamino, and alkylarylamino), acylamino (including carbamoyl,and ureido), alkylcarbonyloxy, arylcarbonyloxy, alkoxycarbonyloxy,alkoxycarbonyl, carboxy, carboxylate, aminocarbonyl, mono anddialkylaminocarbonyl, cyano, azido, halogen, hydroxyl, nitro,trifluoromethyl, thio, alkylthio, arylthio, alkylthiocarbonyl,thiocarboxylate, lower alkyl, lower alkenyl, lower alkynyl, cycloalkyl,heterocycloalkyl, aryl, heteroaryl, lower alkoxy, aryloxy,aryloxycarbonyloxy, benzyloxy, benzyl, sulfinyl, alkylsulfinyl,sulfonyl, sulfate, sulfonate, sulfonamide, phosphate, phosphonato,phosphinato, oxo, guanidine, imino, formyl and the like. Any of theabove substituents can be further substituted if permissible, e.g., ifthe group contains an alkyl group, an aryl group, or other.

The term “solvate” refers to a physical association of a compound withone or more solvent molecules, whether organic or inorganic. Thisphysical association includes hydrogen bonding. In certain instances, asolvate will be capable of isolation, for example when one or moresolvent molecules are incorporated in the crystal lattice of acrystalline solid. “Solvate” encompasses both solution-phase andisolable solvates. Exemplary solvates include, without limitation,hydrates, ethanolates, methanolates, hemiethanolates, and the like.

A “pharmaceutically acceptable salt” of a compound means a salt of acompound that is pharmaceutically acceptable. Desirable are salts of acompound that retain or improve the biological effectiveness andproperties of the free acids and bases of the parent compound as definedherein or that take advantage of an intrinsically basic, acidic orcharged functionality on the molecule and that are not biologically orotherwise undesirable. Examples of pharmaceutically acceptable salts arealso described, for example, in Berge et al., “Pharmaceutical Salts”, J.Pharm. Sci. 66, 1-19 (1977). Non-limiting examples of such saltsinclude:

(1) acid addition salts, formed on a basic or positively chargedfunctionality, by the addition of inorganic acids such as hydrochloricacid, hydrobromic acid, hydroiodic acid, sulfuric acid, sulfamic acid,nitric acid, phosphoric acid, carbonate forming agents, and the like; orformed with organic acids such as acetic acid, propionic acid, lacticacid, oxalic, glycolic acid, pivalic acid, t-butylacetic acid,β-hydroxybutyric acid, valeric acid, hexanoic acid,cyclopentanepropionic acid, pyruvic acid, malonic acid, succinic acid,malic acid, maleic acid, fumaric acid, tartaric acid, citric acid,benzoic acid, 3-(4-hydroxybenzoyl)benzoic acid, cinnamic acid, mandelicacid, methanesulfonic acid, ethanesulfonic acid, 1,2-ethanedisulfonicacid, 2-hydroxyethanesulfonic acid, cyclohexylaminosulfonic acid,benzenesulfonic acid, sulfanilic acid, 4-chlorobenzenesulfonic acid,2-napthalenesulfonic acid, 4-toluenesulfonic acid, camphorsulfonic acid,3-phenyl propionic acid, lauryl sulphonic acid, lauryl sulfuric acid,oleic acid, palmitic acid, stearic acid, lauric acid, embonic (pamoic)acid, palmoic acid, pantothenic acid, lactobionic acid, alginic acid,galactaric acid, galacturonic acid, gluconic acid, glucoheptonic acid,glutamic acid, naphthoic acid, hydroxynapthoic acid, salicylic acid,ascorbic acid, stearic acid, muconic acid, and the like;

(2) base addition salts, formed when an acidic proton present in theparent compound either is replaced by a metal ion, including, an alkalimetal ion (e.g., lithium, sodium, potassium), an alkaline earth ion(e.g., magnesium, calcium, barium), or other metal ions such asaluminum, zinc, iron and the like; or coordinates with an organic basesuch as ammonia, ethylamine, diethylamine, ethylenediamine,N,N′-dibenzylethylenediamine, ethanolamine, diethanolamine,triethanolamine, tromethamine, N-methylglucamine, piperazine,chloroprocain, procain, choline, lysine and the like.

Pharmaceutically acceptable salts may be synthesized from a parentcompound that contains a basic or acidic moiety, by conventionalchemical methods. Generally, such salts are prepared by reacting thefree acid or base forms of compounds with a stoichiometric amount of theappropriate base or acid in water or in an organic solvent, or in amixture of the two. Salts may be prepared in situ, during the finalisolation or purification of a compound or by separately reacting acompound in its free acid or base form with the desired correspondingbase or acid, and isolating the salt thus formed. The term“pharmaceutically acceptable salts” also include zwitterionic compoundscontaining a cationic group covalently bonded to an anionic group, asthey are “internal salts”. It should be understood that all acid, salt,base, and other ionic and non-ionic forms of compounds described hereinare intended to be encompassed. For example, if a compound is shown asan acid herein, the salt forms of the compound are also encompassed.Likewise, if a compound is shown as a salt, the acid and/or basic formsare also encompassed.

The terms “Abeta”, “Aβ”, “β-amyloid”, and “amyloid-β” are usedinterchangeably herein to refer to any peptide resulting frombeta-secretase mediated cleavage of Amyloid Precursor Protein (APP),including for example peptides of 37, 38, 39, 40, 41, 42, and 43 aminoacids, and extending from the beta-secretase cleavage site to aminoacids 37, 38, 39, 40, 41, 42, or 43. Other forms of the above peptidesare also included, e.g., N-terminal truncated species such aspyroglutamic forms pE3-40, pE3-42, pE3-43, pE11-42, pE11-43, and thelike. For convenience of nomenclature, “Aβ₁₋₄₂” may be referred toherein as “Aβ(1-42)” or simply as “Aβ₄₂” (and likewise for any otheramyloid peptides discussed herein). As used herein, the terms “Abeta”,“Aβ”, “β-amyloid”, and “amyloid-β” are synonymous, referringcollectively to truncated and non-truncated peptide species of thesequence between β- and γ-cleavage sites of APP.

The terms “amyloid-β disease” and “amyloid-β related disease” are usedto refer to a variety of diseases and conditions associated withamyloid-β, including, without limitation, mild cognitive impairment(MCI); vascular dementia; early-onset Alzheimer's disease; Alzheimer'sdisease, including sporadic (non-hereditary) Alzheimer's disease andfamilial (hereditary) Alzheimer's disease; age-related cognitivedecline; cerebral amyloid angiopathy (CAA); hereditary cerebralhemorrhage; senile dementia; Down's syndrome; degenerative dementia;dementia or mixed vascular and degenerative origin; dementia associatedwith Parkinson's disease; dementia associated with progressivesupranuclear palsy; dementia associated with cortical basaldegeneration; dementia associated with diffuse Lewy body type ofAlzheimer's disease; inclusion body myositis (IBM); and age-relatedmacular degeneration (ARMD).

As used herein, “AUC” refers to the area under a curve representing theconcentration of a compound in a biological sample from a subject as afunction of time following administration of the compound to thesubject. Non-limiting examples of such biological samples includebiological fluids such as plasma, blood, cerebrospinal fluid (CSF), andsaliva; organ homogenates such as brain and liver homogenates; and thelike. The AUC can be determined by measuring the concentration of acompound in a biological sample such as the plasma, blood, CSF or brainhomogenate using methods such as liquid chromatography-tandem massspectrometry (LC/MS/MS), at various time intervals, and calculating thearea under the concentration-versus-time curve. Suitable methods forcalculating the AUC from a drug concentration-versus-time curve are wellknown in the art. As relevant to the disclosure here, an AUC for 3APScan be determined by measuring the concentration of 3APS in the plasma,blood, CSF or brain homogenate of a subject following oraladministration of a compound described herein to the subject.

“Bioavailability” refers to the rate and amount of a compound thatreaches the systemic circulation of a subject following administrationof the compound or a prodrug thereof to the subject and can bedetermined by evaluating, for example, the plasma or bloodconcentration-versus-time profile for the compound. Parameters useful incharacterizing a plasma or blood concentration-versus-time curve includethe area under the curve (AUC), the time to peak concentration(T_(max)), and the maximum compound concentration (C_(max)). “C_(max)”is the maximum concentration of a compound in the biological sample of asubject following administration of a dose of the compound to thesubject. “T_(max)” is the time to the maximum concentration (C_(max)) ofa compound in the biological sample of a subject followingadministration of a dose of the compound to the subject. Bioavailabilityis often expressed as F (%) referring to the ratio in percentage of theAUC of the compound for a specific mode of administration (e.g., orally)over AUC of the compound after intravenous (IV) administration.

“Bioequivalence” refers to equivalence of the rate and extent ofabsorption of a therapeutic agent, such as a compound, afteradministration of equal doses of the agent to a patient. As used herein,two plasma or blood concentration profiles are bioequivalent if the 90%confidence interval for the ratio of the mean response of the twoprofiles is within the limits of 0.8 and 1.25. The mean responseincludes at least one of the characteristic parameters of a profile suchas C_(max), T_(max), or AUC.

As used herein the term “effective amount” refers to the amount or doseof a therapeutic agent, such as a compound, upon single or multiple doseadministration to a subject, which provides the desired therapeutic,diagnostic, or prognostic effect in the subject. An effective amount canbe readily determined by an attending physician or diagnostician usingknown techniques and by observing results obtained under analogouscircumstances. In determining the effective amount or dose of compoundadministered, a number of factors are considered including, but notlimited to: the size, age, and general health of the subject; thespecific disease involved; the degree of or involvement or the severityof the disease or condition to be treated; the response of theindividual subject; the particular compound administered; the mode ofadministration; the bioavailability characteristics of the preparationadministered; the dose regimen selected; the use of concomitantmedication(s); and other relevant considerations.

As used herein, the term “therapeutic bio-distribution of 3APS” refersto one or more pharmacokinetic parameters of 3APS which affect 3APStherapeutic activity. Examples of such pharmacokinetic (PK) parametersinclude, but are not limited to: bioavailability of 3APS, AUC of 3APS,brain levels of 3APS, CSF levels of 3APS, C_(max) of 3APS, T_(max) of3APS, and/or bio-absorption of 3APS, etc.

In some embodiments, therapeutic efficacy of 3APS may be increased byincreasing therapeutic bio-distribution of 3APS, e.g., increasingbioavailability of 3APS, increasing stability of 3APS, reducingmetabolism of 3APS, and/or increasing other pharmacokinetic parametersof 3APS after administration, as compared to administration ofnon-isotope enriched 3APS or prodrugs thereof.

As used herein, the terms “increased (or like terms, e.g., increasing,increase in, etc.) therapeutic effectiveness/efficacy of 3APS” and“enhanced (or like terms, e.g., enhancing, enhancement, etc.)therapeutic effectiveness/efficacy of 3APS” refer to an increasedeffectiveness of 3APS as measured, e.g., by one or more parameterslisted under “therapeutic bio-distribution of 3APS” above, e.g., by 5%,10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99%, 125%, etc., oreven more, e.g., 2, or 4 fold, or even more when administered to asubject, e.g., animal or human, which increase is with respect to thesame equivalent molar dose of non-isotope enriched 3APS. In someembodiments, such % increases are achieved also with respect to 3APSadministered orally in the formulation of Table 3 of U.S. ApplicationPublication No. 2006-0079578, published Apr. 13, 2016. Effectiveness canalso be as measured, for example, by effect on characteristics of adisease such as Alzheimer's disease, e.g., by the reduction of plaquesor AD load in the brain, or by an improvement in selected manifestationsof the disease, e.g., memory loss, cognition, reasoning, judgment,orientation, etc. Such effects may be measured using cognitive testssuch as ADAS-COG, MMSE, CDR, and the like. See U.S. ApplicationPublication No. 2006-0079578, published Apr. 13, 2016, for details onhow to measure effects on characteristics of such diseases.

The term “lessening metabolism of 3APS” (or related terms such asreduction, less, lowering, reducing, lowered, etc) refers to decreasingthe degree or amount of metabolism of 3APS, e.g., first-pass metabolismin the GI tract or liver of 3APS, by e.g., 5%, 10%, 20%, 30%, 40%, 50%,60%, 70%, 80%, 90%, 95%, 99%, or even 100%, which decrease is withrespect to the degree or amount of metabolism of 3APS that occurs whenthe same equivalent molar dose of non-isotope enriched 3APS isadministered. In some embodiments, such % decreases may be achieved alsowith respect to 3APS administered orally in the formulation of Table 3of U.S. Application Publication No. 2006-0079578, published Apr. 13,2016.

The term “reduction of side effects of 3APS” refers to decreasing theamount of or severity of one or more side effects of 3APS by, e.g., 5%,10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, 99%, or 99.9%, or even100%, which decrease is with respect to the amount of or severity of aside effect of 3APS that is exhibited when the same equivalent molardose of non-isotope enriched 3APS is administered. In some embodimentssuch % decreases are achieved also with respect to 3APS administeredorally in the formulations of Table 3 of U.S. Application PublicationNo. 2006-0079578, published Apr. 13, 2016. More generally, the termslessening etc., increasing etc., refer in context herein to thepercentage changes, e.g., by 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%,90%, 95%, 99%, 125%, etc., or even more, e.g., 2, or 4 fold, or evenmore.

In some embodiments, AUC of 3APS is increased by at least about 20% byadministration of a compound of the present invention as compared toadministration of the same equivalent molar dose of non-isotope enriched3APS or a prodrug thereof. In some embodiments, oral AUC of 3APS isincreased by at least about 20% by administration of a compound of thepresent invention as compared to oral administration of the sameequivalent molar dose of non-isotope enriched 3APS or a prodrug thereof.In other embodiments, AUC is increased by at least about 5%, at leastabout 10%, at least about 25%, at least about 30%, or at least about40%.

The contents of U.S. Application Publication No. 2006-0079578, publishedApr. 13, 2016, are incorporated herein by reference in their entirety,including the pharmacokinetic data therein (such as the data in Example1 and Table 3 therein) for providing inter alia a comparative basis forthe effects achieved by administration of compounds provided herein.

“Pharmaceutically acceptable” refers to drugs, medicaments, inertingredients etc., which the term describes, suitable for use in contactwith the tissues of humans and lower animals without undue toxicity,incompatibility, instability, irritation, allergic response, and thelike, commensurate with a reasonable benefit/risk ratio. It preferablyrefers to a compound or composition that is approved or approvable by aregulatory agency of the Federal or state government or listed in theU.S. Pharmacopoeia or other generally recognized pharmacopoeia for usein animals and more particularly in humans.

“Pharmaceutically acceptable vehicle” refers to a diluent, adjuvant,excipient, or carrier with which a compound is administered.

“Pharmaceutical composition” refers to at least one compound and atleast one pharmaceutically acceptable vehicle, with which the compoundis administered to a patient.

“Preventing” or “prevention” is intended to refer at least the reductionof likelihood of the risk of (or susceptibility to) acquiring a diseaseor disorder (i.e., causing at least one of the clinical symptoms of thedisease not to develop in a patient that may be exposed to orpredisposed to the disease but does not yet experience or displaysymptoms of the disease).

“Treating” or “treatment” of any disease or disorder refers, in someembodiments, to ameliorating at least one disease or disorder (i.e.,arresting or reducing the development of the disease or at least one ofthe clinical symptoms thereof). In certain embodiments “treating” or“treatment” refers to ameliorating at least one physical parameter,which may or may not be discernible by the patient. In certainembodiments, “treating” or “treatment” refers to inhibiting the diseaseor disorder, either physically, (e.g., stabilization of a discerniblesymptom), physiologically, (e.g., stabilization of a physicalparameter), or both. In certain embodiments, “treating” or “treatment”refers to delaying the onset of the disease or disorder. The term“treating” refers to any indicia of success in the treatment oramelioration of an injury, pathology or condition, including anyobjective or subjective parameter such as abatement; remission;diminishing of symptoms or making the injury, pathology or conditionmore tolerable to the subject; slowing in the rate of degeneration ordecline; making the final point of degeneration less debilitating;improving a subject's physical or mental well-being; or, in somesituations, preventing the onset of dementia. The treatment oramelioration of symptoms can be based on objective or subjectiveparameters; including the results of a physical examination, apsychiatric evaluation, or a cognition test such as CDR, MMSE, DAD,ADAS-Cog, or another test known in the art. For example, the methods ofthe invention may successfully treat a subject's dementia by slowing therate of or lessening the extent of cognitive decline.

“Therapeutically effective amount” means the amount of compound that,when administered to a patient for treating or preventing a disease, issufficient to effect such treatment or prevention of the disease. The“therapeutically effective amount” will vary depending on the compound,the disease and its severity, and the age, weight, etc., of the patienthaving the disease to be treated or prevented.

The term “prodrug” and equivalent expressions refer to agents which canbe converted in vitro or in vivo directly or indirectly to an activeform (see, e.g., R. B. Silverman, 1992, “The Organic Chemistry of DrugDesign and Drug Action,” Academic Press, Chap. 8; Bundgaard, Hans;Editor. Neth. (1985), “Design of Prodrugs”. 360 pp. Elsevier, Amsterdam;Stella, V.; Borchardt, R.; Hageman, M.; Oliyai, R.; Maag, H.; Tilley, J.(Eds.) (2007), “Prodrugs: Challenges and Rewards, XVIII, 1470 p.Springer). Prodrugs can be used to alter the bio-distribution (e.g., toallow agents which would not typically enter the reactive site of theprotease) or the pharmacokinetics for a particular agent. A wide varietyof groups have been used to modify compounds to form prodrugs, forexample, esters, ethers, phosphates, etc. When the prodrug isadministered to a subject, the group is cleaved, enzymatically ornon-enzymatically, reductively, oxidatively, or hydrolytically, orotherwise to reveal the active form. As used herein, “prodrug” includespharmaceutically acceptable salts thereof, or pharmaceuticallyacceptable solvates as well as crystalline forms of any of theforegoing. Prodrugs are frequently, although not necessarily,pharmacologically inactive until converted to the parent drug.

The term “ester” refers to compounds that can be represented by theformula RCOOR (carboxylic ester) or the formula RSO₃R′ (sulfonateester), where the group R can be, for example 3APS or the 3-aminopropanepart thereof, and the group R′ can be another organic group. Thesecompounds are usually respectively formed by the reaction between acarboxylic or a sulfonic acid and an alcohol usually with theelimination of water.

The term “amino acid” generally refers to an organic compound comprisingboth a carboxylic acid group and an amine group. The term “amino acid”includes both “natural” and “unnatural” or “non-natural” amino acids.Additionally, the term amino acid includes O-alkylated or N-alkylatedamino acids, as well as amino acids having nitrogen or oxygen-containingside chains (such as Lys, Cys, or Ser) in which the nitrogen or oxygenatom has been acylated or alkylated. Amino acids may be pure L or Disomers or mixtures of L and D isomers, including (but not limited to)racemic mixtures.

The term “natural amino acid” and equivalent expressions refer toL-amino acids commonly found in naturally-occurring proteins. Examplesof natural amino acids include, without limitation, alanine (Ala),cysteine (Cys), aspartic acid (Asp), glutamic acid (Glu), phenylalanine(Phe), glycine (Gly), histidine (His), isoleucine (Ile), lysine (Lys),leucine (Leu), methionine (Met), asparagine (Asn), proline (Pro),glutamine (Gln), arginine (Arg), serine (Ser), threonine (Thr), valine(Val), tryptophan (Trp), tyrosine (Tyr), β-alanine (β-Ala), andγ-aminobutyric acid (GABA).

The term “unnatural amino acid” refers to any derivative of a naturalamino acid including D forms, and α- and β-amino acid derivatives. Theterms “unnatural amino acid” and “non-natural amino acid” are usedinterchangeably herein. It is noted that certain amino acids, e.g.,hydroxyproline, that are classified as a non-natural amino acid herein,may be found in nature within a certain organism or a particularprotein. Amino acids with many different protecting groups appropriatefor immediate use in the solid phase synthesis of peptides arecommercially available. In addition to the twenty most common naturallyoccurring amino acids, the following examples of non-natural amino acidsand amino acid derivatives may be used according to the invention(common abbreviations in parentheses): 2-aminoadipic acid (Aad),3-aminoadipic acid (β-Aad), 2-aminobutyric acid (2-Abu),α,β-dehydro-2-aminobutyric acid (8-AU), 1-aminocyclopropane-1-carboxylicacid (ACPC), aminoisobutyric acid (Aib), 3-aminoisobutyric acid (β-Aib),2-amino-thiazoline-4-carboxylic acid, 5-aminovaleric acid (5-Ava),6-aminohexanoic acid (6-Ahx), 2-aminoheptanoic acid (Ahe),8-aminooctanoic acid (8-Aoc), 11-aminoundecanoic acid (11-Aun),12-aminododecanoic acid (12-Ado), 2-aminobenzoic acid (2-Abz),3-aminobenzoic acid (3-Abz), 4-aminobenzoic acid (4-Abz),4-amino-3-hydroxy-6-methylheptanoic acid (Statine, Sta), aminooxyaceticacid (Aoa), 2-aminotetraline-2-carboxylic acid (ATC),4-amino-5-cyclohexyl-3-hydroxypentanoic acid (ACHPA),para-aminophenylalanine (4-NH₂-Phe), 2-aminopimelic acid (Apm),biphenylalanine (Bip), para-bromophenylalanine (4-Br-Phe),ortho-chlorophenylalanine (2-C₁-Phe), meta-chlorophenylalanine(3-Cl-Phe), para-chlorophenylalanine (4-C₁-Phe), meta-chlorotyrosine(3-C₁-Tyr), para-benzoylphenylalanine (Bpa), tert-butylglycine (TLG),cyclohexylalanine (Cha), cyclohexylglycine (Chg), desmosine (Des),2,2-diaminopimelic acid (Dpm), 2,3-diaminopropionic acid (Dpr),2,4-diaminobutyric acid (Dbu), 3,4-dichlorophenylalanine (3,4-C₁₋₂-Phe),3,4-difluororphenylalanine (3,4-F₂-Phe), 3,5-diiodotyrosine(3,5-I₂-Tyr), N-ethylglycine (EtGly), N-ethylasparagine (EtAsn),ortho-fluorophenylalanine (2-F-Phe), meta-fluorophenylalanine (3-F-Phe),para-fluorophenylalanine (4-F-Phe), meta-fluorotyrosine (3-F-Tyr),homoserine (Hse), homophenylalanine (Hfe), homotyrosine (Htyr),hydroxylysine (Hyl), allo-hydroxylysine (aHyl), 5-hydroxytryptophan(5-OH-Trp), 3- or 4-hydroxyproline (3- or 4-Hyp), para-iodophenylalanine(4-I-Phe), 3-iodotyrosine (3-I-Tyr), indoline-2-carboxylic acid (Idc),isodesmosine (Ide), allo-isoleucine (a-Ile), isonipecotic acid (Inp),N-methylisoleucine (Melle), N-methyllysine (MeLys), meta-methyltyrosine(3-Me-Tyr), N-methylvaline (MeVal), 1-naphthylalanine (1-Nal),2-naphthylalanine (2-Nal), para-nitrophenylalanine (4-NO₂-Phe),3-nitrotyrosine (3-NO₂-Tyr), norleucine (Nle), norvaline (Nva),ornithine (Orn), ortho-phosphotyrosine (H₂PO₃-Tyr),octahydroindole-2-carboxylic acid (Oic), penicillamine (Pen),pentafluorophenylalanine (F₅-Phe), phenylglycine (Phg), pipecolic acid(Pip), propargylglycine (Pra), pyroglutamic acid (PGLU), sarcosine(Sar), tetrahydroisoquinoline-3-carboxylic acid (Tic), thienylalanine,and thiazolidine-4-carboxylic acid (thioproline, Th).

Where multiple substituents are indicated as being attached to astructure, it is to be understood that the substituents can be the sameor different. Thus for example “R_(m) optionally substituted with 1, 2or 3 R_(q) groups” indicates that R_(m) is substituted with 1, 2, or 3R_(q) groups where the R_(q) groups can be the same or different.

Isotope-Enriched Compounds

Isotopic enrichment is a process by which the relative abundance of theisotopes of a given element are altered, thus producing a form of theelement that has been enriched (i.e., increased) in one particularisotope and reduced or depleted in its other isotopic forms. As usedherein, an “isotope-enriched” compound or derivative refers to acompound in which one or more specific isotopic form has been increased,i.e., one or more of the elements has been enriched (i.e., increased) inone or more particular isotope. Generally, in an isotope-enrichedcompound or derivative, a specific isotopic form of an element at aspecific position of the compound is increased. It should be understoodhowever that isotopic forms of two or more elements in the compound maybe increased. Further, an isotope-enriched compound may be a mixture ofisotope-enriched forms that are enriched for more than one particularisotope, more than one element, or both.

Under normal conditions, the natural abundances for deuterium (D or ²H)(a stable isotope of hydrogen with a mass approximately twice that ofthe usual isotope), nitrogen-15 (¹⁵N), carbon-13 (¹³C), oxygen-18 (¹⁸O),and oxygen-17 (¹⁷O) are 0.016%, 0.37%, 1.11%, 0.204%, and 0.037%,respectively. As used herein, an “isotope-enriched” compound orderivative possesses a level of an isotopic form that is higher than thenatural abundance of that form. The level of isotope-enrichment willvary depending on the natural abundance of a specific isotopic form. Insome embodiments, the level of isotope-enrichment for a compound, or foran element in a compound, may be from about 2 to about 100 molar percent(%), e.g., about 2%, about 5%, about 17%, about 30%, about 51%, about83%, about 90%, about 95%, about 96%, about 97%, about 98%, greater thanabout 98%, about 99%, or 100%. In one embodiment, the level ofisotope-enrichment in an isotope-enriched compound of the invention(e.g., 3APS, a compound of any of Formulae (I)-(VI), etc.) is about 5%or higher, or about 10% or higher. In another embodiment, the level ofisotope-enrichment in an isotope-enriched compound of the invention(e.g., 3APS, a compound of any of Formulae (I)-(VI), etc.) is about 20%or higher, or about 50% or higher. In yet another embodiment, the levelof isotope-enrichment in an isotope-enriched compound of the invention(e.g., 3APS, a compound of any of Formulae (I)-(VI), etc.) is about 75%or higher, or about 90% or higher. In still another embodiment, thelevel of isotope-enrichment in an isotope-enriched compound of theinvention (e.g., 3APS, a compound of any of Formulae (I)-(VI), etc.) isabout 95% or higher, or 100%. It should be understood that the level ofisotope-enrichment for a particular compound, or a particular element ofa compound, will be selected based on several properties of the compoundsuch as its chemical, pharmacokinetic, and therapeutic profiles, withthe aim of improving the compound's therapeutic efficacy, therapeuticbio-distribution, bioavailability, metabolism, stability, and/orpharmacokinetic profile.

As used herein, an “element of natural abundance” and an “atom ofnatural abundance” refers to the element or atom respectively having theatomic mass most abundantly found in nature. For example, hydrogen ofnatural abundance is 1H (protium); nitrogen of natural abundance is 14N;oxygen of natural abundance is 160; carbon of natural abundance is ¹²C;and so on. A “non-isotope enriched” compound is a compound in which allthe atoms or elements in the compound are isotopes of natural abundance,i.e., all the atoms or elements have the atomic mass most abundantlyfound in nature. This is in contrast to an isotope-enriched compound inwhich one or more element is enriched for one or more specific isotopicform that is not the isotope of natural abundance. Non-isotope enrichedcompounds are excluded from compounds of the present invention providedherein.

As used herein, the terms “Compounds of the present invention”,“Compounds of the invention”, and equivalent expressions refers toisotope-enriched compounds provided herein as being useful for at leastone purpose of the invention, e.g., those encompassed by structuralFormulae such as (I), (II), (III), (IV), (V), and (VI), and includesspecific compounds mentioned herein such as those in Tables 1-4 as wellas their pharmaceutically acceptable salts, esters, chelates, hydrates,and solvates.

Embodiments herein may exclude one or more of the compounds of theinvention. In some embodiments, N-acetyl-3-amino-1-propanesulfonic acidis excluded from compounds of the invention.

As would be understood by a person of ordinary skill in the art, therecitation of “a compound” is intended to include salts, esters,solvates, hydrates, oxides, and inclusion complexes of that compound aswell as any stereoisomeric form or polymorphic form, or a mixture of anysuch forms of that compound in any ratio. Thus, in accordance with someembodiments of the invention, a compound as described herein, includingin the contexts of pharmaceutical compositions and methods of treatmentis provided as the salt form.

It should be understood that compounds described herein may contain oneor more chiral centers and/or double bonds and therefore, may exist asstereoisomers, such as double-bond isomers (i.e., geometric isomers),enantiomers, or diastereomers. Chemical structures disclosed herein areintended to encompass all possible enantiomers and stereoisomers of theillustrated compounds including the stereoisomerically pure form (e.g.,geometrically pure, enantiomerically pure, or diastereomerically pure)and enantiomeric and stereoisomeric mixtures. Enantiomeric andstereoisomeric mixtures can be resolved into their component enantiomersor stereoisomers using separation techniques or chiral synthesistechniques well known to the skilled artisan, e.g., chiralchromatography (such as chiral HPLC), immunoassay techniques, or the useof covalently (such as Mosher's esters) and non-covalently (such aschiral salts) bound chiral reagents to respectively form adiastereomeric mixture which can be separated by conventional methods,such as chromatography, distillation, crystallization or sublimation,the chiral salt or ester is then exchanged or cleaved by conventionalmeans, to recover the desired isomers. The compounds may also exist inseveral tautomeric forms including the enol form, the keto form, andmixtures thereof. The chemical structures depicted herein are alsointended to encompass all possible tautomeric forms of the illustratedcompounds.

Compounds may exist in unsolvated forms as well as solvated forms,including hydrated forms. In general, compounds may be hydrated orsolvated. Certain compounds may exist in multiple crystalline oramorphous forms. In general, all physical forms are intended to beencompassed herein.

The term “3APS” is used herein to refer to 3-amino-1-propanesulfonicacid, which is also known by alternate names including tramiprosate,Alzhemed™, and homotaurine, in which one or more atoms in the compoundmay or may not be in isotope-enriched form. “3APS” as used herein refersto any compound having the same structure regardless of how many orwhich atoms are in isotope-enriched form. For example, “3APS” is usedherein to refer to compound 1 and compound 7 among the examples of thepresent invention.

Compounds described herein include, but are not limited to, theiroptical isomers, racemates, and other mixtures thereof. In thosesituations, the single enantiomers or diastereomer, i.e., opticallyactive forms, can be obtained by asymmetric synthesis or by resolutionof the racemates. Resolution of the racemates can be accomplished, forexample, by conventional methods such as crystallization in the presenceof a resolving agent, or chromatography, using, for example a chiralhigh-pressure liquid chromatography (HPLC) column. In addition, suchcompounds include Z- and E-forms (or cis- and trans-forms) of compoundswith carbon-carbon double bonds. Where compounds described herein existin various tautomeric forms, the term “compound” is intended to includeall tautomeric forms of the compound. Such compounds also includecrystal forms including polymorphs and clathrates. Similarly, the term“salt” is intended to include all tautomeric forms and crystal forms ofthe compound.

The configuration of any carbon-carbon double bond appearing herein isselected for convenience only and is not intended to designate aparticular configuration; thus a carbon-carbon double bond depictedarbitrarily herein as E may be Z, E, or a mixture of the two in anyproportion.

For compounds provided herein, it is intended that, in some embodiments,salts thereof are also encompassed, including pharmaceuticallyacceptable salts. Those skilled in the art will appreciate that manysalt forms (e.g., TFA salt, tetrazolium salt, sodium salt, potassiumsalt, etc) are possible; appropriate salts are selected based onconsiderations known in the art. The term “pharmaceutically acceptablesalt” refers to salts prepared from pharmaceutically acceptablenon-toxic acids or bases including inorganic acids and bases and organicacids and bases. For example, for compounds that contain a basicnitrogen, salts may be prepared from pharmaceutically acceptablenon-toxic acids including inorganic and organic acids. Suitablepharmaceutically acceptable acid addition salts for the compounds of thepresent invention include without limitation acetic, benzenesulfonic(besylate), benzoic, camphorsulfonic, citric, ethenesulfonic, fumaric,gluconic, glutamic, hydrobromic, hydrochloric, isethionic, lactic,maleic, malic, mandelic, methanesulfonic, mucic, nitric, pamoic,pantothenic, phosphoric, succinic, sulfuric, tartaric acid,p-toluenesulfonic, and the like. When the compounds contain an acidicside chain, suitable pharmaceutically acceptable base addition salts forthe compounds of the present invention include without limitationmetallic salts made from aluminum, calcium, lithium, magnesium,potassium, sodium and zinc or organic salts made from lysine,N,N′-dibenzylethylenediamine, chloroprocaine, choline, diethanolamine,ethylenediamine, meglumine (N-methylglucamine), and procaine.

Compositions

In an embodiment, there is provided a pharmaceutical compositioncomprising a compound of the invention, e.g., a compound of any one ofFormulae (I)-(VI), or a pharmaceutically acceptable salt, ester, orsolvate thereof, and a pharmaceutically acceptable carrier. In anembodiment, there is provided a pharmaceutical composition comprising acompound in any one of Tables 1-4, or a pharmaceutically acceptable saltthereof, and a pharmaceutically acceptable carrier. In anotherembodiment, there is provided a pharmaceutical composition comprising acompound of any one of Formulae (I)-(VI) or a compound in any one ofTables 1-4, or a pharmaceutically acceptable salt thereof, and apharmaceutically acceptable carrier, with the proviso that the compoundis not N-acetyl-3-amino-1-propanesulfonic acid.

The preparation of pharmaceutical compositions can be carried out asknown in the art (see, for example, Remington: The Science and Practiceof Pharmacy, 20^(th) Edition, 2000). For example, a therapeutic compoundand/or composition, together with one or more solid or liquidpharmaceutical carrier substances and/or additives (or auxiliarysubstances) and, if desired, in combination with other pharmaceuticallyactive compounds having therapeutic or prophylactic action, are broughtinto a suitable administration form or dosage form which can then beused as a pharmaceutical in human or veterinary medicine. Pharmaceuticalpreparations can also contain additives, of which many are known in theart, for example fillers, disintegrants, binders, lubricants, wettingagents, stabilizers, emulsifiers, dispersants, preservatives,sweeteners, colorants, flavorings, aromatizers, thickeners, diluents,buffer substances, solvents, solubilizers, agents for achieving a depoteffect, salts for altering the osmotic pressure, coating agents orantioxidants.

The term “pharmaceutical composition” means a composition comprising acompound as described herein and at least one component comprisingpharmaceutically acceptable carriers, diluents, adjuvants, excipients,or vehicles, such as preserving agents, fillers, disintegrating agents,wetting agents, emulsifying agents, suspending agents, sweeteningagents, flavoring agents, perfuming agents, antibacterial agents,antifungal agents, lubricating agents and dispensing agents, dependingon the nature of the mode of administration and dosage forms.

The term “pharmaceutically acceptable carrier” is used to mean anycarrier, diluent, adjuvant, excipient, or vehicle, as described herein.Examples of suspending agents include ethoxylated isostearyl alcohols,polyoxyethylene sorbitol and sorbitan esters, microcrystallinecellulose, aluminum metahydroxide, bentonite, agar-agar and tragacanth,or mixtures of these substances. Prevention of the action ofmicroorganisms can be ensured by various antibacterial and antifungalagents, for example, parabens, chlorobutanol, phenol, sorbic acid, andthe like. It may also be desirable to include isotonic agents, forexample sugars, sodium chloride, and the like. Prolonged absorption ofthe injectable pharmaceutical form can be brought about by the use ofagents delaying absorption, for example, aluminum monosterate andgelatin. Examples of suitable carriers, diluents, solvents, or vehiclesinclude water, ethanol, polyols, suitable mixtures thereof, vegetableoils (such as olive oil), and injectable organic esters such as ethyloleate. Examples of excipients include lactose, milk sugar, sodiumcitrate, calcium carbonate, and dicalcium phosphate. Examples ofdisintegrating agents include starch, alginic acids, and certain complexsilicates. Examples of lubricants include magnesium stearate, sodiumlauryl sulphate, talc, as well as high molecular weight polyethyleneglycols.

The term “pharmaceutically acceptable” means it is, within the scope ofsound medical judgment, suitable for use in contact with the cells of asubject, e.g., humans and animals, without undue toxicity, irritation,allergic response, and the like, and are commensurate with a reasonablebenefit/risk ratio.

A pharmaceutically acceptable carrier may include any and all solvents,dispersion media, coatings, antibacterial and antifungal agents,isotonic and absorption delaying agents, and the like that arephysiologically compatible. In one embodiment, the carrier is suitablefor parenteral administration. Alternatively, the carrier may besuitable for intravenous, intraperitoneal, intramuscular, sublingual ororal administration. In other embodiments, the carrier is suitable fortopical administration or for administration via inhalation.Pharmaceutically acceptable carriers include sterile aqueous solutionsor dispersions and sterile powders for the extemporaneous preparation ofsterile injectable solutions or dispersion. The use of such media andagents for pharmaceutically active substances is well known in the art.Except insofar as any conventional media or agent is incompatible withthe active compound, use thereof in the pharmaceutical compositionsprovided herein is contemplated. Supplementary active compounds can alsobe incorporated into the compositions. For example, a pharmaceuticalcomposition provided herein may further comprise at least one additionalAlzheimer's disease therapeutic, as discussed below.

A pharmaceutical composition provided herein can be administered orally,for example in the form of pills, tablets, lacquered tablets,sugar-coated tablets, granules, hard and soft gelatin capsules, aqueous,alcoholic or oily solutions, syrups, emulsions or suspensions, orrectally, for example in the form of suppositories. Administration canalso be carried out parenterally, for example subcutaneously,intramuscularly or intravenously in the form of solutions for injectionor infusion. Other suitable administration forms are, for example,percutaneous or topical administration, for example in the form ofointments, creams, tinctures, sprays or transdermal therapeutic systems,or the inhalative administration in the form of nasal sprays or aerosolmixtures, or, for example, microcapsules, implants or wafers.

In some embodiments, pharmaceutical compositions provided herein aresuitable for oral administration. For example, a pharmaceuticalcomposition may be in the form of a hard shell gelatin capsule, a softshell gelatin capsule, a cachet, a pill, a tablet, a lozenge, a powder,a granule, a pellet, a pastille, or a dragee. Alternatively, apharmaceutical composition may be in the form of a solution, an aqueousliquid suspension, a non-aqueous liquid suspension, an oil-in-waterliquid emulsion, a water-in-oil liquid emulsion, an elixir, or a syrup.Pharmaceutical compositions may or may not be enteric coated. In someembodiments, pharmaceutical compositions are formulated for controlledrelease, such as delayed or extended release.

In further embodiments, compounds and compositions thereof may beformulated in multi-dose forms, i.e., in the form of multi-particulatedosage forms (e.g., hard gelatin capsules or conventional tabletsprepared using a rotary tablet press) comprising one or more bead orminitab populations for oral administration. The conventional tabletsrapidly disperse on entry into the stomach. The one or more coated beador minitab populations may be compressed together with appropriateexcipients into tablets (for example, a binder, a diluent/filler, and adisintegrant for conventional tablets.

Tablets, pills, beads, or minitabs of the compounds and compositions ofthe compounds may be coated or otherwise compounded to provide a dosageform affording the advantage of controlled release, including delayed orextended release, or to protect from the acid conditions of the stomach.For example, the tablet or pill can include an inner dosage and an outerdosage component, the latter being in the form of a coating over theformer. The two components can be separated by a polymer layer thatcontrols the release of the inner dosage.

In certain embodiments, the layer may comprise at least one entericpolymer. In further embodiments, the layer may comprise at least oneenteric polymer in combination with at least one water-insolublepolymer. In still further embodiments, the layer may comprise at leastone enteric polymer in combination with at least one water-solublepolymer. In yet further embodiments, the layer may comprise at least oneenteric polymer in combination with a pore-former.

In certain embodiments, the layer may comprise at least onewater-insoluble polymer. In still further embodiments, the layer maycomprise at least one water-insoluble polymer in combination with atleast one water-soluble polymer. In yet further embodiments, the layermay comprise at least one water-insoluble polymer in combination with apore-former.

Representative examples of water-soluble polymers includepolyvinylpyrrolidone (PVP), hydroxypropyl methylcellulose (HPMC),hydroxypropylcellulose (HPC), polyethylene glycol, and the like.

Representative examples of enteric polymers include esters of celluloseand its derivatives (cellulose acetate phthalate, hydroxypropylmethylcellulose phthalate, hydroxypropyl methylcellulose acetatesuccinate), polyvinyl acetate phthalate, pH-sensitive methacrylicacid-methylmethacrylate copolymers and shellac. These polymers may beused as a dry powder or an aqueous dispersion. Some commerciallyavailable materials that may be used are methacrylic acid copolymerssold under the trademark Eudragit (LI 00, S I 00, L30D) manufactured byRohm Pharma, Cellacefate (cellulose acetate phthalate) from EastmanChemical Co., Aquateric (cellulose acetate phthalate aqueous dispersion)from FMC Corp. and Aqoat (hydroxypropyl methylcellulose acetatesuccinate aqueous dispersion) from Shin Etsu K.K.

Representative examples of useful water-insoluble polymers includeethylcellulose, polyvinyl acetate (for example, Kollicoat SR#30D fromBASF), cellulose acetate, cellulose acetate butyrate, neutral copolymersbased on ethyl acrylate and methylmethacrylate, copolymers of acrylicand methacrylic acid esters with quaternary ammonium groups such asEudragit NE, RS and RS30D, RL or RL30D and the like.

Any of the above polymers may be further plasticized with one or morepharmaceutically acceptable plasticizers. Representative examples ofplasticizers include triacetin, tributyl citrate, triethyl citrate,acetyl tri-n-butyl citrate diethyl phthalate, castor oil, dibutylsebacate, acetylated monoglycerides and the like or mixtures thereof.The plasticizer, when used, may comprise about 3 to 30 wt. % and moretypically about 10 to 25 wt. % based on the polymer. The type ofplasticizer and its content depends on the polymer or polymers andnature of the coating system (e.g., aqueous or solvent based, solutionor dispersion based and the total solids).

Pharmaceutical compositions typically must be sterile and stable underthe conditions of manufacture and storage. A composition can beformulated as a solution, microemulsion, liposome, or other orderedstructure suitable to high drug concentration. The carrier can be asolvent or dispersion medium containing, for example, water, ethanol,polyol (for example, glycerol, propylene glycol, and liquid polyethyleneglycol, and the like), and suitable mixtures thereof. The properfluidity can be maintained, for example, by the use of a coating such aslecithin, by the maintenance of the required particle size in the caseof dispersion and by the use of surfactants. In many cases, it will bepreferable to include isotonic agents, for example, sugars, polyalcoholssuch as mannitol, sorbitol, or sodium chloride in the composition.Prolonged absorption of injectable compositions can be brought about byincluding in the composition an agent which delays absorption, forexample, monostearate salts and gelatin. Moreover, a compound can beadministered in a time release formulation, for example in a compositionwhich includes a slow release polymer. The compound can be prepared withcarriers that will protect against rapid release, such as a controlledrelease formulation, including implants and microencapsulated deliverysystems. Biodegradable, biocompatible polymers can be used, such asethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen,polyorthoesters, polylactic acid and polylactic, polyglycolic copolymers(PLG).

Many methods for the preparation of such formulations are generallyknown to those skilled in the art. Sterile injectable solutions can beprepared by incorporating an active compound, such as a compound ofFormulae (I)-(VI) provided herein, in the required amount in anappropriate solvent with one or a combination of ingredients enumeratedabove, as required, followed by filtered sterilization. Generally,dispersions are prepared by incorporating the active compound into asterile vehicle that contains a basic dispersion medium and the requiredother ingredients from those enumerated above. In the case of sterilepowders for the preparation of sterile injectable solutions, commonmethods of preparation are vacuum drying and freeze-drying which yieldsa powder of the active ingredient plus any additional desired ingredientfrom a previously sterile-filtered solution thereof. Compounds may alsobe formulated with one or more additional compounds that enhance theirsolubility.

It is often advantageous to formulate compositions (such as parenteralcompositions) in dosage unit form for ease of administration anduniformity of dosage. The term “unit dosage form” refers to a physicallydiscrete unit suitable as unitary dosages for human subjects and otheranimals, each unit containing a predetermined quantity of activematerial calculated to produce the desired therapeutic effect, inassociation with a suitable pharmaceutical carrier. The specificationfor the dosage unit forms of the invention may vary and are dictated byand directly dependent on (a) the unique characteristics of thetherapeutic compound and the particular therapeutic effect to beachieved, and (b) the limitations inherent in the art of compoundingsuch a therapeutic compound for the prevention or treatment of anamyloid-β related disease. Dosages are discussed further below.

In some embodiments, there are provided pharmaceutical compositions thatcomprise an effective amount of a compound and/or composition describedherein, and a pharmaceutically acceptable carrier. In an embodiment,there are provided pharmaceutical compositions for the treatment orprevention of an amyloid-β related disease, comprising a compounddescribed herein, or a pharmaceutically acceptable salt thereof, and apharmaceutically acceptable carrier. In another embodiment, there isprovided a pharmaceutical composition for the prevention or treatment ofan amyloid-β related disease such as Alzheimer's disease, thecomposition comprising a compound described herein, or apharmaceutically acceptable salt thereof, and a pharmaceuticallyacceptable carrier.

Methods of Use of Compounds and Compositions

In another aspect, there are provided methods for prevention ortreatment of an amyloid-β related disease in a subject by administeringan effective amount of a compound or composition described herein. In arelated aspect, there are provided methods for prevention or treatmentof an amyloid-β related disease in a subject in need thereof byadministering an effective amount of a compound or composition describedherein.

The term “subject” includes living organisms with an amyloid-β relateddisease, or who are susceptible to or at risk of an amyloid-β relateddisease, e.g., due to a genetic predisposition or mutation. Examples ofsubjects include humans, monkeys, cows, rabbits, sheep, goats, pigs,dogs, cats, rats, mice, and transgenic species thereof. The term“subject” generally includes animals susceptible to states characterizedby an amyloid-β related disease, e.g., mammals, e.g. primates, e.g.humans. The animal can also be an animal model for a disorder, e.g., atransgenic mouse model, and the like.

In some embodiments, a subject is in need of treatment by the methodsprovided herein, and is selected for treatment based on this need. Asubject in need of treatment is art-recognized, and includes subjectsthat have been identified as having a disease or condition (e.g., mildcognitive impairment (MCI), Alzheimer's disease, dementia, etc.), orhaving a symptom of such a disease or condition, or being at risk ofsuch a disease or condition, and would be expected, based on diagnosis,e.g., medical diagnosis, to benefit from treatment (e.g., curing,healing, preventing, alleviating, relieving, altering, remedying,ameliorating, improving, or affecting the disease or disorder, thesymptom of the disease or disorder, or the risk of the disease ordisorder).

In some embodiments, a subject is an ApoE4+(also referred to herein as“ApoE4 positive” or simply “ApoE4”) subject, i.e., a subject having atleast one ε4 allele of the apolipoprotein E (ApoE) gene. An ApoE4positive subject may carry one or two copies of the ApoE4 allele. The ε4allele of apolipoprotein E gene is the strongest genetic risk factor forpatients with late-onset Alzheimer's disease (AD). ApoE4+ subjects withat least one ε4 allele account for 50%-60% of AD cases vs. 25%prevalence in healthy individuals. ApoE4+AD patients present withdecreased age of onset, increased severity and accelerated progressionof AD. Subjects with two ε4 alleles account for 10%-14% of AD andexhibit an even more aggressive disease progression. ε4 allele leads toan increased brain Aβ amyloid deposition, increased CSF tau and p-tau,and faster cognitive decline. In addition, demented patients carryingone or two ε4 alleles of ApoE are more likely to have AD, resulting insignificantly reduced rate of disease misdiagnosis in clinical studies(2% vs. 42% in non-ApoE4 patients).

In some embodiments, treatment or prevention are within the context ofthe present invention if there is a measurable difference between theperformances of subjects treated using the compounds and methodsprovided herein as compared to members of a placebo group, historicalcontrol, or between subsequent tests given to the same subject.

It should be understood that the dosage or amount of a compound and/orcomposition used, alone or in combination with one or more activecompounds to be administered, depends on the individual case and is, asis customary, to be adapted to the individual circumstances to achievean optimum effect. Dosing and administration regimens are within thepurview of the skilled artisan, and appropriate doses depend upon anumber of factors within the knowledge of the ordinarily skilledphysician, veterinarian, or researcher (e.g., see Wells et al. eds.,Pharmacotherapy Handbook, 2nd Edition, Appleton and Lange, Stamford,Conn. (2000); PDR Pharmacopoeia, Tarascon Pocket Pharmacopoeia 2000,Deluxe Edition, Tarascon Publishing, Loma Linda, Calif. (2000)). Forexample, dosing and administration regimens may depend on the nature andthe severity of the disorder to be treated, and also on the sex, age,weight and individual responsiveness of the human or animal to betreated, on the efficacy and duration of action of the compounds used,on whether the therapy is acute or chronic or prophylactic, and/or onwhether other active compounds are administered in addition to thetherapeutic molecule(s).

Thus the dose(s) of a compound or composition will vary depending upon avariety of factors including, but not limited to: the activity,biological and pharmacokinetic properties and/or side effects of thecompound being used; the age, body weight, general health, gender, anddiet of the subject; the time of administration, the route ofadministration, the rate of excretion, and any drug combination, ifapplicable; the effect which the practitioner desires the compound tohave upon the subject; and the properties of the compound beingadministered (e.g. bioavailability, stability, potency, toxicity, etc).Such appropriate doses may be determined as known in the art. When oneor more of the compounds of the invention is to be administered tohumans, a physician may for example, prescribe a relatively low dose atfirst, subsequently increasing the dose until an appropriate response isobtained.

There are no particular limitations on the dose of each of the compoundsfor use in compositions provided herein. Exemplary doses includemilligram or microgram amounts of the compound per kilogram of subjector sample weight (e.g., about 50 micrograms per kilogram to about 500milligrams per kilogram, about 1 milligram per kilogram to about 100milligrams per kilogram, about 1 milligram per kilogram to about 50milligram per kilogram, about 1 milligram per kilogram to about 10milligrams per kilogram, or about 3 milligrams per kilogram to about 5milligrams per kilogram). Additional exemplary doses include doses ofabout 5 to about 500 mg, about 25 to about 300 mg, about 25 to about 200mg, about 50 to about 150 mg, or about 50, about 100, about 150 mg,about 200 mg, about 250 mg, or about 500 mg and, for example, daily ortwice daily, or lower or higher amounts.

In some embodiments, the dose range for adult humans is generally from0.005 mg to 10 g/day orally. Tablets or other forms of presentationprovided in discrete units may conveniently contain an amount of acompound (e.g., of Formula I, Formula II, Formula III, Formula IV,Formula V, or Formula VI) which is effective at such dosage or as amultiple of the same, for instance, units containing 5 mg to 500 mg,usually around 10 mg to 200 mg. A dosage unit (e.g., an oral dosageunit) can include from, for example, 1 to 30 mg, 1 to 40 mg, 1 to 100mg, 1 to 300 mg, 1 to 500 mg, 2 to 500 mg, 3 to 100 mg, 5 to 20 mg, 5 to100 mg (e.g. 1 mg, 2 mg, 3 mg, 4 mg, 5 mg, 6 mg, 7 mg, 8 mg, 9 mg, 10mg, 11 mg, 12 mg, 13 mg, 14 mg, 15 mg, 16 mg, 17 mg, 18 mg, 19 mg, 20mg, 25 mg, 30 mg, 35 mg, 40 mg, 45 mg, 50 mg, 55 mg, 60 mg, 65 mg, 70mg, 75 mg, 80 mg, 85 mg, 90 mg, 95 mg, 100 mg, 150 mg, 200 mg, 250 mg,300 mg, 350 mg, 400 mg, 450 mg, or 500 mg) of a compound describedherein.

In some embodiments, the dosage range for oral administration isgenerally about 0.001 mg to about 2000 mg of a compound per kg bodymass. In some embodiments, the oral dose is 0.01 mg to 100 mg per kgbody mass, 0.1 mg to 50 mg per kg body mass, 0.5 mg to 20 mg per kg bodymass, or 1 mg to 10 mg per kg body mass. In some embodiments, the oraldose is 5 mg of a compound per kg body mass.

In further embodiments, the dose is about 10 mg to about 1000 mg,including all ranges and subranges there between, e.g., about 10 mg toabout 900 mg, about 10 mg to about 800 mg, about 10 to about 700 mg,about 10 mg to about 600 mg, about 10 mg to about 500 mg, about 10 mg toabout 400 mg, about 10 mg to about 300 mg, about 10 mg to about 250 mg,about 10 mg to about 200 mg, about 10 mg to about 150 mg, about 10 mg toabout 100 mg, about 10 mg to about 50 mg, about 50 mg to about 900 mg,about 50 mg to about 800 mg, about 50 to about 700 mg, about 50 mg toabout 600 mg, about 50 mg to about 500 mg, about 50 mg to about 400 mg,about 50 mg to about 300 mg, about 50 mg to about 250 mg, about 50 mg toabout 200 mg, about 50 mg to about 150 mg, about 50 mg to about 100 mg,about 100 mg to about 900 mg, about 100 mg to about 800 mg, about 100 toabout 700 mg, about 100 mg to about 600 mg, about 100 mg to about 500mg, about 100 mg to about 400 mg, about 100 mg to about 300 mg, about100 mg to about 250 mg, about 100 mg to about 200 mg, about 100 mg toabout 150 mg, about 150 mg to about 200 mg, about 150 mg to about 250mg, about 150 to about 300 mg, about 150 mg to about 400 mg, about 150mg to about 500 mg, about 200 mg to about 900 mg, about 200 mg to about800 mg, about 200 to about 700 mg, about 200 mg to about 500 mg, about200 mg to about 400 mg, about 200 mg to about 300 mg, about 200 mg toabout 250 mg, about 300 mg to about 900 mg, about 300 mg to about 800mg, about 300 to about 700 mg, about 300 to about 600 mg, about 300 mgto about 500 mg, about 300 mg to about 400 mg, about 400 mg to about 900mg, about 400 mg to about 800 mg, about 400 to about 700 mg, about 400to about 600 mg, about 400 mg to about 500 mg, about 500 mg to about 900mg, about 500 mg to about 800 mg, about 500 to about 700 mg, about 500to about 600 mg, about 100 mg to about 500 mg, about 100 mg to about 400mg, about 100 mg to about 300 mg, or about 100 mg to about 250 mg. In anembodiment, the range is about 150 mg to about 400 mg.

In still further embodiments, the dose is 10 mg, 25 mg, 50 mg, 60 mg, 70mg, 75 mg, 80 mg, 85 mg, 90 mg, 100 mg, 105 mg, 110 mg, 115 mg, 120 mg,125 mg, 130 mg, 135 mg, 140 mg, 145 mg, 150 mg, 160 mg, 170 mg, 180 mg,190 mg, 200 mg, 225 mg, 250 mg, 275 mg, 300 mg, 350 mg, 400 mg, 450 mg,500 mg, 550 mg, 600 mg, 650 mg, 700 mg, 750 mg, 800 mg, 850 mg, 900 mg,950 mg, or 1000 mg.

Administration of compounds and compositions provided herein can becarried out using known procedures, at dosages and for periods of timeeffective to achieve a desired purpose. Dosage regimens can be adjustedto provide the optimum therapeutic response. For example, severaldivided doses may be administered daily or the dose may beproportionally reduced as indicated by the exigencies of the therapeuticsituation. In some embodiments, a compound or composition isadministered at an effective dosage sufficient to prevent or treat anamyloid-β related disease, e.g., Alzheimer's disease, in a subject.Further, a compound or composition may be administered using anysuitable route or means, such as without limitation via oral,parenteral, intravenous, intraperitoneal, intramuscular, sublingual,topical, or nasal administration, via inhalation, or via such otherroutes as are known in the art.

In some embodiments, the efficacy of a compound may be determinedthrough use of a cognitive test known in the art, such as the ADAS-cog(Alzheimer's Disease Assessment Scale-cognitive subscale). ADAS wasdesigned to measure the severity of the most important symptoms ofAlzheimer's disease (AD). The ADAS-Cog helps evaluate cognition anddifferentiates between normal cognitive functioning and impairedcognitive functioning. It is especially useful for determining theextent of cognitive decline and can help evaluate which stage ofAlzheimer's disease a person is in, based on his answers and score. TheADAS-Cog can be used in clinical trials in order to determineincremental improvements or declines in cognitive functioning. Anincreased ADAS-Cog score compared to placebo demonstrates improvedcognitive functioning.

The compounds and compositions provided herein may be administered once,twice, three, or four times daily, using any suitable mode describedabove. Also, in certain embodiments, administration or treatment withthe compounds according to any of the formulae described herein may becontinued for a number of weeks; for example, commonly treatment wouldcontinue for at least 2 weeks, 4 weeks, 8 weeks, 12 weeks, 16 weeks, 20weeks, 24 weeks, 28 weeks, 32 weeks, 36 weeks, 40 weeks, 44 weeks, 48weeks, 52 weeks, 56 weeks, 60 weeks, 64 weeks, 68 weeks, 72 weeks, 76weeks, 80 weeks, 84 weeks, 88 weeks, 92 weeks, 96 weeks, 100 weeks, or104 weeks. In yet further embodiments, administration or treatment withthe compounds according to any of the formulae described herein may becontinued for a number of months; for example, commonly treatment wouldcontinue for at least 2 months, 4 months, 6 months, 8 months, 10 months,12 months, 15 months, 18 months, 20 months, or 24 months. In stillfurther embodiments, administration or treatment with the compoundsaccording to any of the formulae described herein may be continuedindefinitely. In still further embodiments, administration or treatmentwith the compounds according to any of the formulae described herein maybe continued until the ADAS-Cog score improves by about 1.5-fold toabout 4.5-fold. In some aspects, the improvement in score is about1.5-fold, about 2.0-fold, about 3.5-fold, about 4.0-fold, about4.5-fold, about 5.0-fold, about 7.5-fold, about 10.0-fold, about15.0-fold. In particular aspects, the improvement is about 1.5-fold toabout 10.0-fold.

It should be understood that compounds and/or compositions providedherein may be used alone or in combination with other therapies.Non-limiting examples of other amyloid-β related disease therapiesinclude cognitive enhancers (e.g., acetylcholinesterase inhibitors, NMDAreceptor antagonists), other amyloid-β binding compounds, and so on.Thus, compounds and/or compositions described herein may be administeredalone or in combination with one or more additional therapy that may beavailable over-the-counter or by prescription. The latter can beadministered before, after or simultaneously with the administration ofthe compounds and/or compositions described herein. U.S. PatentApplication Publication No. 2005/0031651 (incorporated herein byreference) provides a long but non-exhaustive list of “therapeuticdrugs” that can be useful, in combination, according to the invention.Non-limiting examples of therapeutic drugs to be used with the compoundsor pharmaceutical compositions provided herein are therapeutic drugsuseful in the prevention or treatment of Alzheimer's Disease (AD) or itssymptoms, including but not limited to donepezil (Aricept™), memantine(Namenda™), rivastigmine (Exelon™), Galanthamine (Reminyl™ andR-flurbiprofen (Flurizan™). The compounds and compositions according tothe invention could also be combined with vaccines and antibodies forthe prevention or treatment of AD.

Kits

Compound and compositions provided herein may be packaged as part of akit, optionally including a container (e.g. packaging, a box, a vial,etc). The kit may be commercially used according to the methodsdescribed herein and may include instructions for use in such methods.Additional kit components may include acids, bases, buffering agents,inorganic salts, solvents, antioxidants, preservatives, or metalchelators. The additional kit components may be present as purecompositions, or as aqueous or organic solutions that incorporate one ormore additional kit components. Any or all of the kit componentsoptionally further comprise buffers.

EXAMPLES

The present invention will be more readily understood by referring tothe following examples, which are provided to illustrate the inventionand are not to be construed as limiting the scope thereof in any manner.

Unless defined otherwise or the context clearly dictates otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skill in the art to which thisinvention belongs. It should be understood that any methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of the invention.

General Methods for Preparation and Use of Compounds of the Invention.

General Method A. Preparation and Use of 3-Amino-1-Propanesulfonic Acid(3APS) Sodium Salt.

3APS of natural abundance or isotope-enriched was dissolved in water,followed by addition of 1 molar equivalent of sodium hydroxide. Themixture was kept at room temperature (r.t.) for 10 min., concentrated todryness, and further dried under vacuum. The solid residue was sodiumsalt of 3APS, which was used in the following synthesis withoutpurification.

General Method B. De-Salting Using Ion-Exchange Resin.

Crude product containing sodium chloride or sodium bromide (e.g., 2mmol) was dissolved in water (e.g., 5 mL), followed by addition ofAmberlite IR-120 (H-form) (2 mL). The mixture was stirred for 3 min. andfiltered. The resin was washed with water (e.g., 2 mL×3). The filtrateand washings were combined, and treated with resin once more. Anoptional third treatment with resin was done if there was chloride orbromide ion remaining in the solution. The aqueous solution thusobtained was concentrated to dryness (rotary evaporator), and furtherdried to give salt-free product.

Example 1. Synthesis of 3-amino-3,3-dideuterium-1-propanesulfonic acid(1) and sodium 3-amino-3,3-dideuterium-1-propanesulfonate (1s)

3-Hydroxypropanenitrile (26.0 g, 366 mmol, 1.0 eq.) was dissolved in dryTHF (50 mL). The solution was added dropwise to a stirring suspension ofLiAlD₄ (10.0 g, 238 mmol, 0.65 eq.) in dry THF (200 mL). After heatingat reflux overnight, the reaction mixture was hydrolyzed at r.t. by slowaddition of water (4.8 mL), 15% NaOH solution (4.8 mL), and water (14.4mL) subsequently. The mixture was stirred for 2 hours (h), and filteredunder reduced pressure. The organic phase from the filtration wasevaporated to dryness, giving a red oil material, which was used in thenext step without purification.

The oil material (10.0 g, 128 mmol, 1.0 eq.) was dissolved in CHCl₃ (100mL) and stirred at 0° C. To the stirred mixture was added dropwise SOCl₂(18.2 g, 154 mmol, 1.2 eq.). The mixture was heated at reflux overnight,and then evaporated to dryness under reduced pressure. The residualmaterial was purified by column chromatography on silica gel using10-30% MeOH—CH₂Cl₂ as eluent to afford3-chloro-1,1-dideuterium-1-propylamine hydrochloride (10.8 g, 64.4%) asa white solid.

The above obtained white solid material (10.0 g, 76.3 mmol, 1.0 eq.) wasdissolved in water (50 mL), followed by addition of Na₂SO₃ (9.61 g, 76.3mmol, 1.0 eq.). The mixture was heated at reflux overnight andevaporated to dryness under reduced pressure, followed by addition ofconcentrated HCl. The insoluble material (NaCl) was removed byfiltration, and the filtrate was carefully evaporated to dryness. Theresultant was purified by recrystallization using H₂O and EtOH. Thesolid was collected by filtration, and then dried to give the titlecompound (1) as a white solid (9.5 g, 88.3%). ¹H NMR (500 MHz, D₂O): δppm 2.15 (t, J=7.5 Hz, 2H), 3.07 (t, J=7.5 Hz, 2H); ¹³C NMR (125 MHz,D₂O): δ ppm 22.21, 37.74 (m, CD₂), 47.87; m/z (ES⁻) 140.0 (M−H).

To a solution of compound 1 in water (10 mL) was added NaOH (1.0 eq.),and the mixture was stirred for 10 min at r.t. The mixture wasevaporated under reduced pressure to dryness, giving compound 1s, whichwas used for further reaction without purification.

Example 2. Synthesis of3-((L-alanyl)amino)-3,3-dideuterium-1-propanesulfonic acid (2)

Compound 1s (0.30 g, 1.80 mmol, 1.0 eq.) and N-Boc-L-alanine (0.37 g,2.0 mmol, 1.1 eq.) were mixed in dry DMF (10 mL) and cooled to 0° C.,followed by addition of DCC (0.56 g, 2.7 mmol, 1.5 eq.) and HOBt (0.24g, 1.80 mmol, 1.0 eq.) at 0° C. The mixture was stirred overnight atr.t., followed by addition of water (2 mL), and stirred for anadditional hour. The insoluble material was removed by filtration, andthe organic phase of the filtrate was evaporated to dryness. Theresidual material was dissolved in 20 mL water and washed with ethylacetate (2×20 mL). The aqueous layer was evaporated to dryness. Theresidue was purified by column chromatography on silica gel using 10-30%MeOH—CH₂Cl₂ as eluent to afford sodium3-((N-Boc-L-alanyl)amino)-3,3-dideuterium-1-propanesulfonic acid the(0.50 g, 81.3%) as a white solid. This white solid (0.50 g, 1.5 mmol,1.0 eq.) was added to 1N HCl (10 mL); and the mixture was stirred at 50°C. for 2 h, and evaporated to dryness. The salt was removed by usingion-exchange resin (as described in General Method B above). The crudematerial was purified by recrystallization (MeOH and ethyl acetate). Thesolid product was collected by filtration, and dried under reducedpressure, giving title compound (2) (277 mg, 87.3%) as a white solid. 1HNMR (500 MHz, D₂O): δ ppm 1.49 (d, J=7.0 Hz, 3H), 1.92 (t, J=8.0 Hz,2H), 2.90 (t, J=8.0 Hz, 2H), 3.97-4.07 (m, 1H), 8.34 (s, 1H); ¹³C NMR(125 MHz, D₂O): δ ppm 16.47, 23.71, 48.30, 49.10, 170.69; m/z (ES⁻)210.8 (M−H).

Example 3. Synthesis of3-(L-serylamino)-3,3-dideuterium-1-propanesulfonic acid (3)

Compound 1s (806 mg, 5.0 mmol, 1.0 eq.) and N-Boc-L-serine (1.03 g, 5.0mmol, 1.0 eq) were mixed in DMF (5 mL), followed by addition ofdiphenylphosphoryl azide (DPPA) (1.51 g, 5.0 mmol, 1.0 eq) and Et₃N(0.77 mL). The mixture was stirred at r.t. overnight, and concentratedunder reduced pressure. The residue was purified by flash columnchromatography (MeOH/DCM, 1:4), giving sodium3-((N-Boc-L-seryl)amino)-3,3-dideuterium-1-propanesulfonic acid (800 mg,58.0%) as a white solid. The solid material (250 mg, 0.71 mmol, 1.0 eq.)was added into 1N HCl aqueous solution (10 mL), and the mixture wasstirred at r.t. for 1 h, concentrated under reduced pressure. The saltwas removed by using ion-exchange resin (as described in General MethodB above). The product was dried under vacuum, affording the titlecompound (3) (150 mg, 92.6%) as a white solid. 1H NMR (500 MHz, D₂O) δppm 1.84-1.94 (m, 2H), 2.78-2.94 (m, 2H), 3.83-3.98 (m, 2H), 4.08-4.14(m, 1H); ¹³C NMR (125 MHz, D₂O) δ ppm 23.70, 37.80, 48.30, 54.57, 60.16,167.59; m/z (ES⁺) 228.9 (M+H).

Example 4. Synthesis of3-((L-valyl)amino)-3,3-dideuterium-1-propanesulfonic acid (4)

Compound 1s (1.63 g, 10.0 mmol, 1.0 eq; prepared from compound 1 andsodium hydroxide) and N-Boc-L-valine (2.60 g, 12.0 mmol, 1.2 eq.) weredissolved in dry DMF (20 mL), followed by, at 0° C., addition ofN,N′-dicyclohexylcarbodiimide (DCC, 2.47 g, 12.0 mmol, 1.2 eq.) andhydroxybenzotriazole (HOBt, 1.35 g, 10.0 mmol, 1.0 eq.). The mixture wasstirred overnight at r.t., followed by addition of water (2 mL), andstirred for one more hour. The insoluble material was removed byfiltration. The organic phase of the filtrate was evaporated to dryness.The residual material was dissolved in water (20 mL) and washed withethyl acetate (2×20 mL). The aqueous phase was evaporated to dryness andthe residue was purified by column chromatography on silica gel using10-30% MeOH—CH₂Cl₂ as eluent, providing sodium3-((N-Boc-L-valyl)amino)-3,3-dideuterium-1-propanesulfonic acid as awhite solid (3.2 g, 88.3%).

The above obtained Boc-protected compound (3.2 g, 8.83 mmol, 1.0 eq.)was stirred in 1N HCl (30 mL) at 50° C. for 2 h. The mixture wasevaporated to dryness and the crude material. The salt was removed usingion-exchange resin (General Method B) and the crude was purified byrecrystallization using MeOH and ethyl acetate. The crystalline solidwas collected by filtration, dried under reduced pressure, giving thetitle compound (4) (1.87 g, 88.1%) as a white solid. 1H NMR (500 MHz,D₂O): δ ppm 0.92-1.06 (m, 6H) 1.98 (t, J=7.5 Hz, 2H), 2.17-2.21 (m, 1H),2.95 (t, J=8.0 Hz, 2H), 3.76 (d, J=6.5 Hz, 1H); ¹³C NMR (125 MHz, D₂O):δ ppm 17.01, 17.57, 23.73, 29.80, 48.40, 58.78, 169.18; m/z (ES⁻) 239.1(M−H).

Example 5. Synthesis of3-((L-phenylalanyl)amino)-3,3-dideuterium-1-propanesulfonic acid (5)

Compound 1s (815 mg, 5.0 mmol, 1.0 eq.) and N-Boc-L-phenylalanine (1.59g, 6.0 mmol, 1.2 eq.) were mixed in dry DMF (20 mL). The mixture wascooled to 0° C., followed by addition of DCC (1.24 g, 6.0 mmol, 1.2 eq.)and HOBt (675 mg, 5.0 mmol, 1.0 eq.) at 0° C. The reaction mixture wasstirred at r.t. overnight, followed by addition of water (2 mL), andthen stirred for 1 h. The solid material was removed by filtration, andthe organic phase of the filtrate was evaporated to dryness. Theresidual material was dissolved in water (20 mL), and the aqueoussolution was washed with ethyl acetate (2×20 mL). The aqueous phase wasseparated and evaporated to dryness. The residual material was purifiedby column chromatography on silica gel (eluent: methanol in CH₂Cl₂, from10 to 30%), affording sodium3-((N-Boc-L-phenylalanyl)amino)-3,3-dideuterium-1-propanesulfonic acid(1.80 g, 87.7%) as a white solid. This white solid (1.80 g, 4.39 mmol,1.0 eq.) was treated with IM HBr (20 mL) at 50° C. for 2 h, then thesolvent was evaporated to dryness. The residual material was purified byrecrystallization (EtOH and ethyl acetate). The solid was collected byfiltration, and dried under reduced pressure, giving the title compound,5, (1.07 g, 84.5%) as a white solid. 1H NMR (500 MHz, D₂O): δ ppm1.67-1.80 (m, 2H), 2.54-2.68 (m, 2H), 3.05-3.28 (m, 2H), 4.14 (t, J=6.5Hz, 1H), 7.28 (d, J=9.0 Hz, 2H), 7.34-7.47 (m, 3H); ¹³C NMR (125 MHz,D₂O): δ ppm 23.44, 36.87, 37.5 (m, CD₂), 48.18, 54.64, 128.04, 129.17,129.27, 133.86, 168.81; m/z (ES⁻) 287.0 (M−H).

Example 6. Synthesis of3-((L-histidyl)amino)-3,3-dideuterium-1-propanesulfonic acidhydrochloride (6)

Compound 1s (0.93 g, 5.74 mmol, 1.0 eq.) and N-Boc-L-histidine (1.47 g,5.74 mmol, 1.0 eq.) were mixed in DMF (10 mL), followed by addition ofDPPA (1.74 g, 1.1 eq.) and Et₃N (0.88 mL, 1.1 eq.). The mixture wasstirred at r.t. overnight. After removal of solvent under reducedpressure, the residual material was purified by flash columnchromatography (MeOH/DCM, 1:3), affording sodium3-((N-Boc-L-histidyl)amino)-3,3-dideuterium-1-propanesulfonic acid (1.4g, 60.9%) as a white solid. The solid was added into 1N HBr aqueoussolution (10 mL). The mixture was stirred at r.t. for 1 h, concentratedunder reduced pressure. The residual material was purified byrecrystallization (EtOH and H₂O). The solid was collected by filtration,and dried under reduced pressure, giving the title compound (6) (1.25 g,99.0%) as a white solid. 1H NMR (500 MHz, D₂O) δ ppm 1.82 (d, J=6.8 Hz,2H), 2.78 (t, J=7.0 Hz, 2H), 3.37 (s, 2H), 4.21 (d, J=6.0 Hz, 1H), 7.44(s, 1H), 8.71 (s, 1H); ¹³C NMR (125 MHz, D₂O) δ ppm 23.55, 25.99, 48.21,52.30, 118.30, 125.91, 134.32, 167.69; m/z (ES⁺) 278.9 (M+H).

Example 7. Synthesis of 3-(¹⁵N-amino)-1-propanesulfonic acid (7)

To a solution of 1,3-propanesultone (0.61 g, 5.0 mmol, 1.0 eq.) in MeOH(10 mL) in a sealed tube was added 15N-labeled ammonium sulfate (1.0 g,7.5 mmol, 1.5 eq.) and NaOH (0.5 g, 12.5 mmol, 2.5 eq.). The mixture wasstirred overnight at 70° C., followed by addition of NaHCO₃ (0.63 g, 7.5mmol, 1.5 eq.) and di-(tert-butyl) dicarbonate (1.64 g, 7.5 mmol, 1.5eq.). After heating at reflux for 3 h, the reaction mixture wasevaporated to dryness. The residual material was treated with MeOH andthe insoluble material was removed by filtration. The filtrate wasevaporated to dryness, and the residual material was purified by flashcolumn chromatography on silica gel (eluent: 30% MeOH-DCM) to afford awaxy solid. This material was treated with 1N HBr (20 mL) and themixture was stirred at 50° C. for 2 h. The mixture was evaporated todryness and the residual material was purified by recrystallization(EtOH and H₂O). The solid was collected by filtration, and dried underreduced pressure, giving 3-(¹⁵N-amino)-1-propanesulfonic acid (7) (398mg, 56.8%) as a white solid. 1H NMR (500 MHz, D₂O): δ ppm 2.06-2.16 (m,2H), 3.01 (t, J=7.5 Hz, 2H), 3.15 (t, J=7.5 Hz, 2H); ¹³C NMR (125 MHz,D₂O): δ ppm 22.23, 38.17 (d, J=5.0 Hz), 47.82; m/z (ES⁺) 140.8 (M+H).

Example 8. Synthesis of 3-(L-valyl-(¹⁵N-amino))-1-propanesulfonic acid(10)

To a solution of 1,3-propanesultone (1.22 g, 10.0 mmol, 1.0 eq.) in 20mL MeOH/H₂O (1:1) in a sealed tube was added ¹⁵N-labeled ammoniumsulfate (2.0 g, 15.0 mmol, 1.5 eq.) and NaOH (1.0 g, 25 mmol, 2.5 eq.).The mixture was stirred overnight at 70° C., followed by addition oftriethylamine (1.51 g, 15.0 mmol, 1.5 eq.) and di-tert-butyl dicarbonate(3.27 g, 15.0 mmol, 1.5 eq.). After heating at reflux for 3 h, thereaction mixture was evaporated to dryness. The residual material wastreated with MeOH and the insoluble material was removed by filtration.The filtrate was evaporated to dryness and the residual material waspurified by flash column chromatography on silica gel (eluent: 30%MeOH-DCM) to afford a waxy solid. This material was treated with 1N HCl(30 mL) and the mixture was stirred at 50° C. for 2 h. The mixture wasevaporated to dryness and the residual material,3-(¹⁵N-amino)-1-propanesulfonic acid (7), was used in the next stepwithout further purification.

To a solution of compound 7 in 10 mL H₂O was added NaOH (0.4 g, 10.0mmol, 1.0 eq.), and the mixture was stirred for 10 min at r.t. Themixture was evaporated to dryness to give sodium salt of 7, which wasused in the next step without further purification.

The sodium salt of 7 (obtained above) and N-Boc-L-valine (3.26 g, 15.0mmol, 1.5 eq.) were mixed in dry DMF (30 mL), cooled to 0° C., followedby addition of DCC (3.09 g, 15.0 mmol, 1.5 eq.) and HOBt (1.35 g, 10.0mmol, 1.0 eq.). The reaction mixture was stirred overnight at r.t.,followed by addition of water (2 mL), and stirred for 1 h. The insolublematerial was removed by filtration, and the organic layer of thefiltrate was evaporated to dryness. The residual material was dissolvedin 20 mL water and the aqueous solution was washed with ethyl acetate(2×20 mL). The aqueous phase was evaporated to dryness; and the residualmaterial was purified by column chromatography on silica gel (eluent: 10to 30% MeOH/CH₂Cl₂), giving a waxy solid, which was treated with 1N HCl(30 mL) and stirred at 50° C. for 2 h. The mixture was evaporated todryness and the salt was removed by using ion-exchange resin (GeneralMethod B). The residual material was purified by recrystallization (EtOHand H₂O). The solid was collected by filtration and dried under reducedpressure, giving the title compound (10) (1.23 g, 51.4%) as a whitesolid. 1H NMR (500 MHz, D₂O): δ ppm 0.99-1.08 (m, 6H), 1.91-2.03 (m,2H), 2.12-2.25 (m, 1H), 2.93 (t, J=9.0 Hz, 2H), 3.32-3.45 (m, 2H), 3.74(d, J=6.0 Hz, 1H); ¹³C NMR (125 MHz, D₂O): δ ppm 16.97, 17.54, 23.88,29.77, 38.03 (d, J=8.8 Hz), 48.39, 58.74 (d, J=8.8 Hz), 169.13 (d,J=17.5 Hz); m/z (ES⁻) 237.9 (M−H).

Example 9. Synthesis of 3-((¹⁸O-L-alanyl)amino)-1-propanesulfonic acid(13)

L-Alanine (0.91 g, 10.2 mmol, 1 eq.) was added to a solution of 4M HClin dioxane (5.2 mL, 20.8 mmol, 2 eq.), followed by addition of H₂ ¹⁸O(1.8 mL; ¹⁸O-enrichment, 98%). The mixture was stirred in a sealed tubeat 100° C. for 24 h, cooled to r.t., and evaporated to dryness. Theresidual material was taken into a solution of 4M HCl in Dioxane (2.6mL, 10.2 mmol, 1 eq.), followed by addition of H₂ ¹⁸O (1.6 mL,¹⁸O-enrichment, 98%). The mixture was stirred in a sealed tube at 100°C. for 24 h, cooled to r.t., and evaporated to dryness under reducedpressure, affording L-alanine-¹⁸O₂.HCl (1.32 g, 100%; ¹⁸O-enrichment,92%) as a white solid. To the solution of L-alanine-¹⁸O₂.HCl (1.32 g,10.2 mmol, 1 eq.) 1 in MeOH (50 mL) was added N,N-diisopropylethylamine(DIPEA) (4.07 mL, 22.5 mmol, 2.2 eq.), followed by addition of Boc₂O(2.55 g, 11.2 mmol, 1.1 eq.). The mixture was stirred at 50° C. for 1 h(the mixture became clear at this point), cooled to r.t., andconcentrated to dryness under reduced pressure, affordingN-Boc-L-alanine-¹⁸O₂ DIPEA salt as a white solid, which was used in thenext step without further purification. The DIPEA salt (1 eq., obtainedfrom the above step) was added to a solution of p-nitrophenol (1.59 g,11.22 mmol, 1.1 eq.) in DMF (40 mL), followed by addition of DCC (3.21g, 15.3 mmol, 1.5 eq.). The mixture was stirred at r.t. overnight. Thereaction mixture was filtered, and the filtrate was concentrated underreduced pressure. The residue was purified by flash columnchromatography (ethyl acetate/pet-ether, 1:10) to afford thecorresponding p-nitrophenyl ester as a white solid. The solid thusobtained was dissolved in DMF (30 mL), followed by addition of sodium3-amino-1-propanesulfonate (1.72 g, 10.2 mmol, 1.0 eq.). The mixture wasstirred at 35° C. overnight, and then concentrated under reducedpressure. The residue was purified by flash column chromatography(eluent: MeOH/DCM, 1:8), affording sodium3-((N-Boc-L-¹⁸O-alanyl)amino)-1-propanesulfonic acid (1.5 g, 4.49 mmol;overall yield for the above steps, 44%) as a white solid. Sodium3-((N-Boc-L-¹⁸O-alanyl)amino)-1-propanesulfonic acid (1.5 g, 4.49 mmol)was dissolved in 1N HCl aqueous solution (20 mL). The mixture wasstirred at r.t. for 1 h, and evaporated to dryness. The salt was removedby using ion-exchange resin (General Method B). The product was driedunder vacuum, affording the title compound (13) (0.78 g, 82.0%) as awhite solid. ¹⁸O-enrichment, 92%; ¹H NMR (D₂O, 500 MHz) δ ppm 1.46-1.51(m, 2H), 1.88-1.97 (m, 2 H), 2.86-2.92 (m, 2H), 3.30-3.37 (m, 2H), 4.20(q, 1H, J=5 Hz); ¹³C NMR (D₂O, 125 MHz) δ ppm 16.45, 23.88, 38.05,48.33, 49.08, 170.62; m/z (ES⁻) 211.0 (M−H).

Example 10. Synthesis of 3-((¹⁸O-L-valyl)amino)-1-propanesulfonic acid(15)

To a solution of L-Valine (1.2 g, 10.2 mmol) in ¹⁸O-water (1.5 g, 75.0mmol, 98 atom % ¹⁸O) was added slowly 4N HCl in 1,4-dioxane (5.1 mL,20.4 mmol). The mixture was sealed with stopper, heated at 100° C. for24 h, and then cooled to r.t., and and evaporated (up to 60° C. bathtemperature) to dryness. The above process was repeated once, giving¹⁸O-L-Valine hydrochloride as a yellow solid (1.57 g, 100%, 91.4 atom %¹⁸O), which was used for the next step directly.

To a solution of ¹⁸O-L-Valine hydrochloride (1.57 g, 10.2 mmol, 1.0 eq.)in MeOH (25 mL) was added DIPEA (2.6 g, 20.4 mmol, 2.0 eq.), followed byaddition of Boc₂O (2.2 g, 10.2 mmol, 1.0 eq.). The mixture was heated at55° C. for 30 min, cooled to r.t., and concentrated in vacuo to dryness,giving N-Boc-L-¹⁸O-valine (used in the next step without purification).This material was taken into CH₂Cl₂ (30 mL), and the solution was cooledto 0° C., followed by addition of 4-nitrophenol (1.5 g, 10.7 mmol, 1.05eq.) and DCC (2.3 g, 11.2 mmol, 1.1 eq.) at 0° C. The mixture wasstirred for 2 h at r.t. TLC analysis (DCM:MeOH=10:1) showed no startingmaterial remaining. The insoluble material was removed by filtration,and washed with DCM (30 mL). The combined filtrate was concentrated, andpurified by silica gel chromatography (EtOAc:hexane, 4:1), giving ayellow liquid (2.8 g, 80.2%). This liquid (2.2 g, 6.4 mmol, 1.0 eq.) andsodium 3-amino-1-propanesulfonate (1.0 g, 6.4 mmol, 1.0 eq.) were mixedin DMF (22 mL). The mixture was stirred at 35° C. for 24 h. The solventwas removed under reduced pressure, and the residue was purified bysilica gel chromatography (DCM:MeOH, 4:1), giving sodium3-((N-Boc-(¹⁸O-L-valyl))amino)-1-propanesulfonic acid as a white solid(1.5 g, 65.0%).

The solution of the above obtained solid (1.5 g, 4.1 mmol) in 1N HCl (20mL) was stirred at 60° C. for 1 h. The solvent was removed under reducedpressure. The salt was removed by using ion-exchange resin (GeneralMethod B). The product was dried under vacuum, affording the titlecompound, 15 (686 mg, 70.0%) as a white solid. ¹⁸O-Enrichment, 94% (byES-MS); ¹H NMR (500 MHz, D₂O) δ ppm 0.98-1.10 (m, 6H), 1.97 (s, 2H),2.20 (d, J=4.8 Hz, 1H), 2.93 (s, 2H), 3.38 (d, J=4.5 Hz, 2H), 3.75 (s,1H); 13C NMR (126 MHz, D₂O) δ ppm 17.05, 17.61, 23.94, 29.82, 38.13,48.47, 58.78, 169.15; m/z (ES⁻) 238.9 (M−H).

Example 11. Synthesis of 3-((¹⁸O-L-phenylalanyl)amino)-1-propanesulfonicacid (16)

To a mixture of L-phenylalanine (1.0 g, 6.05 mmol, 1.0 eq.) and¹⁸O-water (1.3 mL, 98 atom % ¹⁸O) was added a saturated hydrochloride(HCl) solution in 1,4-dioxane (3.0 mL, 12.0 mmol, 2.0 eq.). The mixturewas stirred at 100° C. for 24 h, then cooled to r.t., and evaporated todryness under reduced pressure. To the residual material was added¹⁸O-water (1.5 mL, 98 atom % ¹⁸O), followed by addition of HCl solutionin 1,4-dioxane (1.6 mL). The mixture was stirred at 100° C. for 24 h,then cooled to r.t., and evaporated to dryness under reduced pressure,giving ¹⁸O-L-phenylalanine as a white solid (1.0 g, 100%; 96% of¹⁸O-enrichment).

To ¹⁸O-L-phenylalanine (1.0 g, 6.1 mmol, 1.0 eq.) in methanol (20 mL)was added (Boc)₂O (1.45 g, 6.65 mmol, 1.1 eq.) and triethylamine (1.8 g,18.0 mmol, 3.0 eq.). The mixture was stirred at 30° C. for 2 h, thenevaporated to dryness under reduced pressure. The residue was dissolvedin dichloromethane (10 mL), followed by addition ofdicycylohexylcarbodiimide (1.24 g, 6.1 mmol, 1.0 eq.) andN-hydroxysuccinimide (0.60 g, 6.2 mmol, 1.05 eq.). The mixture wasstirred at r.t. overnight. The insoluble material was removed byfiltration, and the filtrate was evaporated under reduced pressure. Theresidual material was purified by flash column chromatography on silicagel (eluent: CH₂Cl₂/methanol, 10:1), giving a white solid (1.4 g). Thiswhite solid was dissolved in DMF (20 mL), followed by addition of sodium3-aminopropane-1-sulfonate (610 mg, 3.84 mmol). The mixture was stirredat r.t. for 2 h, and solvent was removed in vacuo. The residual materialwas purified by flash column chromatography on silica gel (eluent:CH₂Cl₂/methanol, from 10:1 to 5:1), giving sodium3-((N-Boc-(¹⁸O-L-phenylalanyl))amino)-1-propanesulfonic acid as a whitesolid (1.3 g, 82.0%). The obtained compound was dissolved in 1N HCl (20mL). The mixture was stirred for 4 h, and then concentrated in vacuo.The salt was removed by using ion-exchange resin (General Method B). Tothe residual material was added ethanol (20 mL), and the mixture wasstirred at r.t. for 5 min. The solid was collected by filtration, washedwith ethanol (5 mL), and dried under reduced pressure, affording thetitle compound (400 mg, 40.0%) as a white solid. ¹⁸O-enrichment, 87%; ¹HNMR (500 MHz, D₂O) δ ppm 1.68-1.69 (m, 2H), 3.02-3.10 (m, 2H), 2.53-2.56(m, 2H), 3.14-3.24 (m, 2H), 4.06 (t, J=8.0 Hz, 0.1H), 7.21 (d, J=7.0 Hz,2H), 7.32-7.37 (m, 3H), 8.09 (s, 1H); ¹³C NMR (125 MHz, D₂O) δ ppm 23.6,36.8, 38.0, 48.1, 54.6, 128.0, 129.1, 129.2, 133.8, 168.7; m/z (ES⁺)288.9 (M+H), 310.9 (M+Na).

Example 12. Synthesis of 3-((¹⁸O-L-histidyl)amino)-1-propanesulfonicacid hydrobromide (17)

L-Histidine (1.55 g, 10 mmol, 1.0 eq.) was added to a solution of 4M HClin Dioxane (7.5 mL, 30 mmol, 3.0 eq.), followed by addition of H₂ ¹⁸O(2.0 g, 98% ¹⁸O-enrichment). The mixture was stirred in a sealed tube at100° C. for 24 h. The reaction mixture was cooled to r.t., and driedunder vacuum. To the residue was added 4M HCl in Dioxane (2.5 mL, 10mmol, 1.0 eq.), followed by addition of H₂ ¹⁸O (2.0 g, ¹⁸O-enrichment,98%). The mixture was stirred in a sealed tube at 100° C. for 24 h. Thereaction mixture was cooled to r.t., evaporated to dryness, and furtherdried under vacuum, to afford L-His-¹⁸O₂-2HCl (2.32 g, 100%, with 93.8%of ¹⁸O-enrichment) as an off-white solid. The ¹⁸O-enriched L-histidinedihydrochloride (2.32 g, 10 mmol, 1.0 eq.) was dissolved in MeOH (50mL), followed by addition of Et₃N (4.55 g, 45 mmol, 4.5 eq.) and Boc₂O(5.45 g, 25 mmol, 2.5 eq.) subsequently. The mixture was stirred at 50°C. for 1 h (the mixture became clear at this point) and then was cooledto r.t., and concentrated under reduced pressure, to afford thecorresponding TEA salt as a light-yellow solid. This light-yellowmaterial (1.0 eq.) was added to a solution of p-nitrophenol (1.39 g, 10mmol, 1.0 eq.) in DCM (40 mL), followed by addition of DCC (2.27 g, 11mmol, 1.1 eq.). The mixture was stirred at r.t. overnight. The insolublematerial was removed by filtration, and the filtrate was concentratedunder reduced pressure. The residual material was purified by flashcolumn chromatography (eluent: DCM/EA/PE, 2:1:7) to afford thecorresponding 4-nitrophenyl ester (3.0 g, 63.0%) as a white solid. Theester (3.0 g, 6.27 mmol, 1.0 eq.) was dissolved in DMF (30 mL), followedby addition of sodium 3-aminopropane-1-sulfonate (1.0 g, 6.27 mmol, 1.0eq.). The mixture was stirred at r.t. overnight. The reaction mixturewas concentrated under reduced pressure, and the residual material waspurified by flash column chromatography (eluent: MeOH/DCM, 1:8) toafford sodium 3-((N,1-bisBoc-(¹⁸O-L-histidyl))amino)-1-propanesulfonicacid (2.27 g, 72.3%) as a white solid. The white solid (2.27 g, 4.7mmol) was taken into 1N HBr aqueous solution (20 mL). The mixture wasstirred at r.t. for 1 h, concentrated under reduced pressure, and driedunder vacuum. The residual material was purified by recrystallization(EtOH and H₂O). The solid was collected by filtration, and dried underreduced pressure, affording the title compound (17) (1.5 g, 92.0%) as awhite solid. ¹⁸O-enrichment, 93.7%; 1H NMR (D₂O, 500 MHz) δ ppm1.77-1.94 (m, 2H), 2.72-2.88 (m, 2H), 3.22-3.32 (m, 1H), 3.32-3.46 (m,3H), 4.18-4.28 (m, 1H), 7.47 (s, 1H), 8.74 (s, 1H); 13C NMR (D₂O, 125MHz) δ ppm 23.75, 25.98, 38.17, 48.26, 52.33, 118.30, 125.95, 134.34,167.68; m/z (ES⁺) 279.0 (M+H).

Example 13. Synthesis of 3-((1-¹³C-L-valyl)amino)-1-propanesulfonic acid(25)

Sodium 3-amino-1-propanesulfonic acid (1.10 g, 6.8 mmol, 1.5 eq.) andN-Boc-L-valine-1-¹³C (1.0 g, 4.61 mmol, 1.0 eq.) were dissolved in dryDMF (10 mL), followed by, at 0° C., addition ofN,N′-dicyclohexylcarbodiimide (DCC, 1.4 g, 6.8 mmol, 1.5 eq.) andhydroxybenzotriazole (HOBt, 0.62 g, 4.61 mmol, 1.0 eq.). The mixture wasstirred overnight at r.t., followed by addition of water (2 mL), andstirred for one more hour. The insoluble material was removed byfiltration. The organic phase of the filtrate was evaporated to dryness.The residual material was dissolved in water (20 mL) and washed withethyl acetate (2×20 mL). The aqueous phase was evaporated to dryness andthe residue was purified by column chromatography on silica gel (eluent,MeOH—CH₂Cl₂, 10-30%), providing sodium3-((N-Boc-1-¹³C-L-valyl)amino)-1-propanesulfonic acid as a white solid(1.2 g, 72.0%).

The above obtained Boc-protected compound (1.2 g, 3.3 mmol, 1.0 eq.) wasstirred in 1N HCl aqueous solution (30 mL) at 50° C. for 2 h. Themixture was evaporated to dryness. The salt was removed usingion-exchange resin (General Method B). The residual material waspurified by recrystallization (EtOH and H₂O). The solid was collected byfiltration and dried under reduced pressure, giving the title compound(25) (0.65 g, 75.4%) as a white solid. 1H NMR (500 MHz, D2O): δ ppm0.97-1.05 (m, 6H), 1.90-2.00 (m, 2H), 2.21-2.23 (m, 1H), 2.91 (t, J=7.5Hz, 2H), 3.29-3.43 (m, 2H), 3.69-3.75 (m, 1H), 8.49 (s, 1H); ¹³C NMR(125 MHz, D2O): δ ppm 16.97, 17.54, 23.87, 29.77, 38.04, 48.39, 58.50,58.92, 169.14, 169.23; m/z (ES⁻) 238.0 (M−H).

Example 14. Synthesis of3-((¹⁸O-L-valyl)amino)-3,3-dideuterium-1-propanesulfonic acid (29)

Compound 1s (250 mg, 1.53 mmol, 1.0 eq.) and N-Boc-L-(1,1-di-¹⁸O)-valine4-notrophenyl ester (624 mg, 1.84 mmol, 1.2 eq.) were mixed in dry DMF(20 mL). The mixture was stirred overnight at r.t., followed byevaporation under reduced pressure to dryness. The residual material waspurified by column chromatography on silica gel (eluent: MeOH in CH₂Cl₂,10 to 30%), affording sodium3-((N-Boc-¹⁸O-L-valyl)amino)-3,3-dideuterium-1-propanesulfonic acid (400mg, 71.7%) as a white solid. This solid material was mixed with 1N HCl(30 mL); and the mixture was stirred at 50° C. for 2 h. The mixture wasevaporated to dryness. The salt was removed by using ion-exchange resin(General Method B). The residual material was purified byrecrystallization (EtOH and H₂O). The solid was collected by filtrationand dried under reduced pressure, giving the title compound 29 (283 mg,89.8%) as a white solid. 1H NMR (500 MHz, D₂O): δ ppm 1.00-1.08 (m, 6H),1.97 (t, J=7.5 Hz, 2H), 2.16-2.26 (m, 1H), 2.94 (t, J=8.0 Hz, 2H), 3.75(d, J=6.0 Hz, 1H), 8.48 (s, 1H); ¹³C NMR (125 MHz, D₂O): δ ppm 17.03,17.59, 23.75, 29.81, 37.59 (m, CD₂), 48.42, 58.79, 169.16; m/z (ES⁻)240.9 (M−H).

Example 15. Synthesis of3-((L-cysteyl)amino-)-3,3-dideuterium-1-propanesulfonic acid (33)

Compound 1s (0.7 g, 4.3 mmol, 1.0 eq.) and N-Boc-L-cysteine (1.4 g, 4.3mmol, 1.0 eq.) were dissolved in dry DMF (15 mL), followed by, at 0° C.,addition of DCC (1.4 g, 6.5 mmol, 1.5 eq.) and HOBt (0.6 g, 4.6 mmol,1.1 eq.). The mixture was stirred overnight at r.t., followed byaddition of water (2 mL), and stirred for one more hour. The insolublematerial was removed by filtration. The organic phase of the filtratewas evaporated to dryness. The residual material was dissolved in water(20 mL) and washed with ethyl acetate (2×20 mL). The aqueous phase wasevaporated to dryness and the residue was purified by columnchromatography on silica gel (eluent: MeOH—CH₂Cl₂, 10-30%), providingsodium N-Boc-3-((L-cysteyl)amino-)-3,3-dideuterium-1-propanesulfonicacid as a white solid (1.2 g, 59.8%). The above obtained Boc-protectedcompound (1.2 g, 2.57 mmol, 1.0 eq.) was stirred in 1N HCl (30 mL) at50° C. for 2 h. The mixture was evaporated to dryness. The salt wasremoved by using ion-exchange resin (General Method B). The residualmaterial was purified by recrystallization (EtOH and H₂O). Thecrystalline solid was collected by filtration and dried under reducedpressure, giving the title compound (33) (0.57 g, 83.3%) as a whitesolid. 1H NMR (500 MHz, D₂O): δ ppm 1.97 (t, J=7.5 Hz, 2H), 2.95 (t,J=6.0 Hz, 2H), 3.01-3.13 (m, 2H), 4.16 (t, J=6.0 Hz, 1H); ¹³C NMR (125MHz, D₂O): δ ppm 23.70, 24.73, 48.34, 54.55, 167.83; m/z (ES⁺) 244.9(M+H).

Example 16. General example for the synthesis of isotope-enriched3-((N-substituted)amino)-1-propanesulfonic acid and its salt

With experimental procedures described in Examples 1 to 15, with orwithout reasonable modification using general synthetic skills in theart, other compounds represented by Formulae I to VI can be synthesized.Examples of such compounds include, but are not limited to,3-(acylamino)-3,3-dideuterium-1-propanesulfonic acid and3-(acyl(¹⁵N-amino))-1-propanesulfonic acid, where the acyl group isselected from arginyl, aspartyl, asparigyl, cystyl, glutamyl,glutaminyl, glycyl, isoleucyl, leucyl, lysyl, methionyl, prolyl,selenocystyl, threonyl, tryptophanyl, tyrosyl, and 4-hydroxyisoleucyl.Similarly, 3-((1-¹³C-acyl)amino)-1-propqnesulfonic acid,3-((1-¹⁸O-acyl)amino)-1-propanesulfonic acid, and3-((1-¹⁷O-acyl)amino)-1-propanesulfonic acid according to Formulae I andVI can be prepared with the same set of acyl groups. The acyl groups mayalso include other natural amino acids and/or carboxylic acids useful inpharmaceutical preparations. The compounds can also be prepared in theirsalt and ester forms using general synthetic skills.

Example 17. Evaluation of Compound Stability in Simulated Gastric Fluid(SGF)

Compounds were evaluated for stability in simulated gastric fluid (SGF).A solution of a compound in SGF (400 μg/mL) was incubated at 37° C. for4 h. An aliquot of the sample was withdrawn, at time 0 and time 4 h, forconcentration analysis on a LC-MS/MS instrument. The initialconcentration (at time 0) of a compound was considered as 1, and theremaining concentration of the compound at 4-h time point was calculatedand expressed as the percentage of the initial concentration. Exemplaryresults for compounds 1, 4, 5, 15, 16, and 17 are given in Table 5.

TABLE 5 Compound stability in SGF. Compound Remaining (%) at 4 h 1 (100)4 107 5  99 15 104 16  96 17 101

Example 18. Evaluation of Compound Stability in Whole Mouse Blood

Compounds were also evaluated for stability in whole mouse blood. Asample of test compound in fresh mouse blood (at a concentration of 1.44μM) was incubated at 37° C. for 4 h. An aliquot of the sample waswithdrawn, at time 5 min. and time 4 h, for concentration analysis on aLC-MS/MS instrument after converting the blood sample to an analyticalsample employing standard sample preparation procedures. The detailedrecovery of the compound was not fully evaluated and optimized. Thesample was analyzed for the parent compound and the therapeuticcompound. Table 6 shows exemplary results for compounds 1, 2, 4, 5, 15,16, 17 and 29 in which the test compound and compound 1 were analyzed at5 min. and/or 4 h.

TABLE 6 Compound stability in mouse blood (initial concentration at 1.44μM). Compound conc. Compound 1 conc. (μM) Compound (μM) at 4 h 5 min. 4h 1 0.98 1.40 0.98 2 0.18 N.D. N.D. 4 0.74 0.03 0.29 5 0.03 0.23 0.60 150.78 0.01 0.20 16 0.74 0.13 0.39 17 1.20 0.02 0.13 29 0.80 0.02 0.20N.D.: Not Detected

Example 19. General Method for Pharmacokinetic Study of Compounds of theInvention

A compound according to the invention is dissolved in water at aconcentration determined by the desired dose and dosing volume for thespecific animal to which the compound is to be administered. Acalculated volume of dosing solution is administered to the animal (PO,SQ, IP, or IV). A blood sample is collected following administration ofthe compound at specific time points (such as 10 min., 30 min., 1 h, 2h, 4 h, 8 h, and 12 h). The blood sample is converted to a plasma sampleusing standard techniques. A brain sample can also be collected aftercomplete perfusion. The plasma and/or brain samples are analyzed todetermine the concentration of relevant compounds (including e.g.,administered compounds, therapeutic compounds (e.g., drugs) andmetabolites).

Example 20. Pharmacokinetic Studies of Compounds of the Invention in anICR Mouse

Forty-two male ICR mice, body-weight of 19 to 21 g, are randomized into7 groups. The animals are administered with an aqueous solution of atest compound by oral gavage. Blood samples are collected into tubespre-loaded with heparin anticoagulating agent, at time 0.167, 0.5, 1, 2,4, 8, and 12 h after administration. Blood samples are centrifuged, andplasma samples are isolated for analysis of the test compound (includingcompounds administered, metabolites, and/or prodrugs). A 400 μL bloodsample is collected from each animal, and then the animal is put tosleep with barbiturate anesthesia; perfusion is performed (through themain vein of the heart) with saline at a rate of 5 mL/min., for 6 min.The brain is collected and kept at −40° C. until the sample is analyzed.The protein in the plasma is precipitated and the analytical sample isanalyzed on an AB4000-Q-Trap UPLC-MS/MS instrument.

The results of an exemplary pharmacokinetic study are presented in FIGS.1 and 2. FIG. 1 shows plasma compound concentration-time curvesfollowing an oral administration of 3APS (of natural abundance, i.e.,not isotope-enriched), compound 1 and compound 4. In the figure, curveslabeled with -♦-, -▪-, and -▴- represent plasma drug concentrationfollowing administration of 3APS (of natural abundance), compounds 1 and4, respectively; and the curve labeled with -x- represents plasmaprodrug concentration following administration of 4. The resultsindicate that at the mole-equivalent oral dose, the isotope-enrichedcompounds 1 and 4 improved plasma drug exposure significantly, withclose to 2-fold increase of Cmax for the drug concentration followingthe administration of 4. Furthermore, 4 (a prodrug of 1) was convertedeasily to 1 in the subject (FIG. 1). In addition, the isotope-enrichedcompounds (1 and 4) delayed drug metabolism.

FIG. 2 shows the plasma concentration of the metabolite (M,2-carboxy-1-ethanesulfonic acid) following an oral administration of3APS (of natural abundance), compound 1, and compound 4, with the curveslabeled with -♦-, -▪-, and -▴- representing 3APS (of natural abundance),1, and 4, respectively. At the 2-h time point, for example, plasma drugconcentrations from the compounds 1 and 4 were higher than that from3APS (of natural abundance), while the concentration of metabolite inplasma was much lower following administration of isotope-enrichedcompounds compared to administration of 3APS (of natural abundance).

Example 21. Pharmacokinetic Studies for 3APS (of Natural Abundance),Compound 1 and Compound 4 in Sprague-Dawley (SD) Rats

Pharmacokinetic studies were performed in Sprague-Dawley (SD) rats. Theexperiments were done using the same protocol described in Example 21,with 18 animals divided into three groups (6 in each group: one groupfor 3APS (of natural abundance), one group for compound 1, and the othergroup for compound 4). The primary PK parameters and results of thestudy are summarized in Table 7.

TABLE 7 PK parameters for 3APS (of natural abundance), compound 1, andcompound 4 in SD rats. Compound 1 (following administration of)Parameter Unit 3APS 1 4 AUC (0-t) μg · h/L 47212 53916 66900 t_(1/2) h3.7 3.7 2.4 T_(max) h 0.5 0.5 0.4 C_(max) μg/L 18707 23017 32216

Example 22. Pharmacokinetic Studies for Compounds in C57Bl6 Mice

Pharmacokinetic studies were performed in C57Bl6 mice. The experimentswere done using the same protocol described in Example 20. For eachcompound, 42 animals were used (6 animals per time point, and 7 timepoints distributed at 10 min, 0.5, 1, 2, 4, 8 and 12 h). The primary PKparameters and results of the study are summarized in Table 8.

TABLE 8 PK parameters from C57Bl6 mouse experiments. Drug MetaboliteProdrug Compd AUC_(t) C_(max) T_(1/2) AUC_(t) C_(max) T_(1/2) AUC_(t)C_(max) T_(1/2) 1 27915 6685 2.1 22615 2795 12.8 n/a n/a n/a 2 2197210513 1.8 12573 1751 11.8 348 472 0.6 3 17258 7020 1.9 14302 2018 4.244735 22300 1.9 4 38926 15622 2.0 21009 2828 5.7 38009 39483 1.5 5 200316426 2.4 2254 347 8.4 782 1092 0.4 6 25379 10013 2.1 24390 3678 3.516623 9920 1.4 13 26574 9930 1.9 21342 3576 4.5 1832 672 0.5 16 93912590 1.0 2155 273 5.1 11891 3843 1.5 17 31443 13888 2.4 23267 3738 3.614236 18983 1.1 n/a: Not applicable

Example 23. Efficacy of Compounds of the Invention in an Animal Model ofAlzheimer's Disease

100 APP/PS1 transgenic mice (7 months old, both male and female) arerandomized into 5 groups (20 in each group): model control, positivecontrol, and test groups of low-, medium-, and high-doses. One group of20 wildtype C57BL/6J mice (7 months old, both male and female) is alsoused as a normal control. After environmental adaptation in the lab for5 days, the animals are treated with vehicle, control compound, or testcompound, respectively, through oral gavage, once a day, six days aweek, for 3 consecutive months. At the end of treatment, animals aresubjected to behavioral evaluation, including the Y-maze test, theMorris water maze test, and other tests designed to measure short- andlong-term memory. Finally, the animals are sacrificed and subjected tovarious biochemical and molecular evaluations, such as Aβ (including1-40 and 1-42, soluble, plaque, and total), β-tau, GSK-3β, SYP, PSD95,NMDAR2B, p-NMDAR2B, CaMKII, p-CaMKII, and the like, and variousparameters for inflammation and related physiological conditions.

Although this invention is described in detail with reference toembodiments thereof, these embodiments are offered to illustrate but notto limit the invention. It is possible to make other embodiments thatemploy the principles of the invention and that fall within its spiritand scope as defined by the claims appended hereto.

The contents of all documents and references cited herein are herebyincorporated by reference in their entirety.

What is claimed is:
 1. A compound of Formula (I), or a pharmaceuticallyacceptable salt or ester thereof:R¹R²X—CR₂—CH₂—CH₂—SO₃H   (I) where: R¹ and R² are independently ahydrogen of natural abundance or a protecting group, wherein saidprotecting group is isotope-enriched or non-isotope enriched, saidprotecting group being selected from acyl, carbonyl, thiocarbonyl, andcarbamoyl groups, wherein at least one of R¹ and R² is a protectinggroup; X is a nitrogen of natural abundance or ¹⁵N, or a combinationthereof; and R is a hydrogen of natural abundance, a deuterium (D) or acombination thereof; provided that at least one of X, R, R¹ and R²comprises an atom that is not of natural abundance; provided that thecompound is not N-acetyl-3-amino-1-propanesulfonic acid.
 2. The compoundof claim 1, wherein: R is a hydrogen of natural abundance and X is ¹⁵N;R is D and X is a nitrogen of natural abundance; R is D and X is ¹⁵N; orR is a hydrogen of natural abundance; X is a nitrogen of naturalabundance; and at least one atom in R¹ and/or R² is not of naturalabundance.
 3. A compound of Formula (II), or a pharmaceuticallyacceptable salt or ester thereof:H₂X—CR₂ ⁻CH₂ ⁻CH₂ ⁻SO₃H   (II) where: X is ¹⁵N; and R is a hydrogen ofnatural abundance, a deuterium (D) or a combination thereof.
 4. Acompound of Formula (III), or a pharmaceutically acceptable salt orester thereof:

where: X is a nitrogen of natural abundance, a ¹⁵N or a combinationthereof; R is a hydrogen of natural abundance, a deuterium (D) or acombination thereof; Y is a carbon of natural abundance, a ¹³C or acombination thereof; Z is a sulfur of natural abundance, an oxygen ofnatural abundance, an ¹⁸O, an ¹⁷O or a combination thereof; and R³ is asubstituting group selected from substituted or unsubstituted alkyl,aryl, amino alkyl, amino arylalkyl, heterocyclyl, alkoxyl, alkylthio,alkylamino, acyloxyl, and thioacyloxyl; provided that at least one of X,R, Y and Z is not an atom of natural abundance; provided that thecompound is not N-acetyl-3-amino-1-propanesulfonic acid.
 5. The compoundof claim 4, wherein: R is not a hydrogen of natural abundance when X isa nitrogen of natural abundance; R³, Y, and Z taken together form anacyl group connected to X, forming an amide bond linkage; or R³ is anatural or unnatural amino acid residue and R³, Y, and Z taken togetherform an acyl group connected to X, the acyl group being derived from anatural or unnatural amino acid.
 6. The compound of claim 5, wherein thenatural or unnatural amino acid is an L-amino acid, a D-amino acid, or amixture thereof.
 7. A compound of Formula (IV), or a pharmaceuticallyacceptable salt or ester thereof:

where: R⁴ is a side chain of a natural or unnatural amino acid; O* is anoxygen atom of natural abundance, an ¹⁸O, an ¹⁷O or a combinationthereof; and C* is a carbon atom of natural abundance, a ¹³C or acombination thereof; X is a nitrogen of natural abundance, a ¹⁵N or acombination thereof; provided that at least one of O*, C*, and X is notan atom of natural abundance; provided that the compound is notN-acetyl-3-amino-1-propanesulfonic acid.
 8. The compound of claim 7,wherein the natural or unnatural amino acid is an L-amino acid, aD-amino acid, or a mixture thereof.
 9. A compound of Formula (V), or apharmaceutically acceptable salt or ester thereof:

where: R⁴ is a side chain of a natural or unnatural amino acid; O* is anoxygen atom of natural abundance, an ¹⁸O, an ¹⁷O or a combinationthereof; and C* is a carbon atom of natural abundance, a ¹³C or acombination thereof; provided that the compound is notN-acetyl-3-amino-1-propanesulfonic acid.
 10. The compound of claim 9,wherein the natural or unnatural amino acid is an L-amino acid, aD-amino acid, or a mixture thereof.
 11. A compound of Formula (VI), or apharmaceutically acceptable salt or ester thereof:

where: R⁴ is a side chain of a natural or unnatural amino acid; O^(#) isan oxygen atom of natural abundance, an ¹⁸O, an ¹⁷O or a combinationthereof; C^(#) is a carbon atom of natural abundance, a ¹³C or acombination thereof; provided that at least one of O^(#) and C^(#) is anisotope-enriched atom; provided that the compound is notN-acetyl-3-amino-1-propanesulfonic acid.
 12. The compound of claim 11,wherein the natural or unnatural amino acid is an L-amino acid, aD-amino acid, or a mixture thereof.
 13. The compound of claim 1, whichis

or a pharmaceutically acceptable salt or ester thereof.
 14. The compoundof claim 1, wherein the level of isotope enrichment in the compound withisotopes that are not of natural abundance is about 2% or more, about 5%or more, about 10% or more, about 20% or more, about 50% or more, about75% or more, about 90% or more, about 95% or more, or 100%.
 15. Apharmaceutical composition comprising the compound of claim 1 and apharmaceutically acceptable carrier.
 16. The pharmaceutical compositionof claim 15, wherein the composition is suitable for oral administrationand is in the form of a hard shell gelatin capsule, a soft shell gelatincapsule, a cachet, a pill, a tablet, a lozenge, a powder, a granule, apellet, a pastille, a dragee, a solution, an aqueous liquid suspension,a non-aqueous liquid suspension, an oil-in-water liquid emulsion, awater-in-oil liquid emulsion, an elixir, or a syrup, optionally whereinthe composition is enteric coated or formulated for controlled release.17. A method for treatment of an amyloid-β related disease in a subjectin need thereof comprising administering to the subject atherapeutically effective amount of the compound of claim 1 or thepharmaceutical composition of claim 15, such that the amyloid-β relateddisease is prevented or treated in the subject, wherein the amyloid-βrelated disease is Alzheimer's disease, mild cognitive impairment (MCI),Down's syndrome, Hereditary Cerebral Hemorrhage with Amyloidosis of theDutch-Type, cerebral amyloid angiopathy, a degenerative dementia, adementia of mixed vascular and degenerative origin, dementia associatedwith Parkinson's disease, dementia associated with progressivesupranuclear palsy, dementia associated with cortical basaldegeneration, or dementia associated with diffuse Lewy body type ofAlzheimer's disease.
 18. The method of claim 17, wherein the subject isApoE4 positive.
 19. A compound which is

or a pharmaceutically acceptable salt or ester thereof.
 20. The compoundof claim 1, wherein one of R¹ and R² is a hydrogen and one of R¹ and R²is a protecting group.